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Hierarchical Interdiffusion Kinetics in Nanoscale Ni/Al Multilayers
Authors:
S. S. Riegler,
I. Gallino,
N. J. Peter,
A. Tarasov,
T. Meyer,
J. Schmauch,
C. Pauly,
M. Frey,
Y. H. Sauni Camposano,
H. Bartsch,
R. Schwaiger,
P. Schaaf,
R. Busch,
J. Arlt
Abstract:
Reactive metallic multilayers store chemical energy that can be released rapidly through interdiffusion and intermetallic formation. Predictive control of this heat release requires distinguishing transport and phase-formation processes that occur in rapid succession. Here we combine free-standing nanoscale Ni/Al multilayers with chip-based flash calorimetry and isoconversional kinetic analysis ov…
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Reactive metallic multilayers store chemical energy that can be released rapidly through interdiffusion and intermetallic formation. Predictive control of this heat release requires distinguishing transport and phase-formation processes that occur in rapid succession. Here we combine free-standing nanoscale Ni/Al multilayers with chip-based flash calorimetry and isoconversional kinetic analysis over five orders of magnitude in heating rate. Selected reaction states are quenched and examined by scanning transmission electron microscopy. This workflow separates pre-ignition interdiffusion into two regimes and quantifies activation energies of (81 $\pm$ 24) and (168 $\pm$ 17) kJ/mol, consistent with grain-boundary and lattice diffusion of Ni in Al, respectively. Microscopy supports this assignment: no significant compositional changes are observed after the first regime, whereas the second increases the Ni content of the Al layers and produces Ni-enriched features spaced by 5$-$10 nm, matching the Al grain size. These results identify the Al grain-boundary network as the dominant low-barrier pathway, providing rapid transport across the Al layers and priming lattice-mediated mixing and intermetallic phase formation. More broadly, the workflow links calorimetric signatures to pathway-specific kinetics and transient microstructures, enabling direct assessment of how microstructural design redirects coupled transport and reaction pathways in reactive multilayers and other materials driven far from equilibrium.
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Submitted 21 August, 2026; v1 submitted 10 June, 2026;
originally announced June 2026.
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Isothermal Annealing Effects on $β$-Relaxations and Crystallization Behaviors in Amorphous GeTe
Authors:
Arune Makareviciute,
Qun Yang,
Tomoki Fujita,
Oliver Gross,
Nico Neuber,
Maximilian Frey,
Jens Moesgaard,
Cecile Chaxel,
Julian Pries,
Mads Ry Vogel Jørgensen,
Frederik Holm Gjørup,
Matthias Wuttig,
Hai-bin Yu,
Jiangjing Wang,
Shuai Wei
Abstract:
A secondary $β$-relaxation process is often the dominant source of atomic dynamics below $T_\mathrm{g}$ in many glass forming systems. Recent studies reported the presence of $β$-relaxations in amorphous phase-change materials (PCMs) and showed that suppressing the $β$-relaxation via annealing in Ge$_{15}$Sb$_{85}$ can effectively slow down its crystallization kinetics. Yet, when Sb is replaced by…
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A secondary $β$-relaxation process is often the dominant source of atomic dynamics below $T_\mathrm{g}$ in many glass forming systems. Recent studies reported the presence of $β$-relaxations in amorphous phase-change materials (PCMs) and showed that suppressing the $β$-relaxation via annealing in Ge$_{15}$Sb$_{85}$ can effectively slow down its crystallization kinetics. Yet, when Sb is replaced by Te, similar annealing protocol has little effect on the Te-rich alloy Ge$_{15}$Te$_{85}$. Here, we investigate amorphous GeTe that is a Sb-free PCM, but with faster crystallization kinetics than Ge$_{15}$Te$_{85}$. Using powder mechanical dynamic spectroscopy, we observe a clear reduction of the excess-wing in the loss modulus upon isothermal annealing, indicating a suppression of its $β$-relaxation. Ultrafast calorimetric analysis and time-resolved optical reflectivity measurements show that, whereas as-deposited GeTe exhibit stochastic crystallization behaviors, annealed samples crystallize more slowly with reduced stochasticity. Synchrotron X-ray scattering experiments reveal reinforced Peierls-like distortions in the amorphous structure after annealing, and demonstrate that, even if annealing introduces nucleation sites, it nonetheless slows down crystallization kinetics. These finding suggests that, in annealed GeTe, crystallization is limited by crystal growth rate, which is retarded through the suppression of $β$-relaxation.
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Submitted 15 October, 2025;
originally announced October 2025.
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Break-down of the relationship between α-relaxation and equilibration in hydrostatically compressed metallic glasses
Authors:
Antoine Cornet,
Jie Shen,
Alberto Ronca,
Shubin Li,
Nico Neuber,
Maximilian Frey,
Eloi Pineda,
Thierry Deschamps,
Christine Martinet,
Sylvie Le Floch,
Daniele Cangialosi,
Yuriy Chushkin,
Federico Zontone,
Marco Cammarata,
Gavin B. M. Vaughan,
Marco di Michiel,
Gaston Garbarino,
Ralf Busch,
Isabella Gallino,
Celine Goujon,
Murielle Legendre,
Geeth Manthilake,
Beatrice Ruta
Abstract:
Glasses encode the memory of any thermo-mechanical treatment applied to them. This ability is associated to the existence of a myriad of metastable amorphous states which can be probed through different experimental pathways. It is usually assumed that this memory can be erased in the supercooled liquid, and that this process occurs on a time scale controlled by the α-relaxation. We find that this…
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Glasses encode the memory of any thermo-mechanical treatment applied to them. This ability is associated to the existence of a myriad of metastable amorphous states which can be probed through different experimental pathways. It is usually assumed that this memory can be erased in the supercooled liquid, and that this process occurs on a time scale controlled by the α-relaxation. We find that this assumption does not apply for hydrostatically compressed glasses. Annealing under pressure a prototypical metallic glass can irreversibly modify its dynamics, thermodynamics and structure, reduce the atomic mobility and lead to structural modifications of the first coordination shells which reduce the thermal stability with respect to a glass annealed in absence of pressure. When heated above their glass transition temperature, these compressed glasses do not convert into the pristine supercooled liquid, implying the existence of an additional process, beyond the α-relaxation, contributing to the equilibrium recovery of the material. These results establish pressure as a powerful tool for engineering non-equilibrium glassy materials with tailored properties, while deepening our understanding of relaxation dynamics in disordered systems under extreme conditions.
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Submitted 8 February, 2026; v1 submitted 20 September, 2024;
originally announced September 2024.
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On the interplay of liquid-like and stress-driven dynamics in a metallic glass former observed by temperature scanning XPCS
Authors:
Maximilian Frey,
Nico Neuber,
Sascha Sebastian Riegler,
Antoine Cornet,
Yuriy Chushkin,
Federico Zontone,
Lucas Ruschel,
Bastian Adam,
Mehran Nabahat,
Fan Yang,
Jie Shen,
Fabian Westermeier,
Michael Sprung,
Daniele Cangialosi,
Valerio Di Lisio,
Isabella Gallino,
Ralf Busch,
Beatrice Ruta,
Eloi Pineda
Abstract:
Modern detector technology and highly brilliant fourth-generation synchrotrons allow to improve the temporal resolution in time-resolved diffraction studies. Profiting from this, we applied temperature scanning X-ray photon correlation spectroscopy (XPCS) to probe the dynamics of a Pt-based metallic glass former in the glass, glass transition region, and supercooled liquid, covering up to six orde…
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Modern detector technology and highly brilliant fourth-generation synchrotrons allow to improve the temporal resolution in time-resolved diffraction studies. Profiting from this, we applied temperature scanning X-ray photon correlation spectroscopy (XPCS) to probe the dynamics of a Pt-based metallic glass former in the glass, glass transition region, and supercooled liquid, covering up to six orders of magnitude in time scales. Our data demonstrates that the structural alpha-relaxation process is still observable in the glass, although it is partially masked by a faster source of decorrelation observed at atomic scale. We present an approach that interprets these findings as the superposition of heterogeneous liquid-like and stress-driven ballistic-like atomic motions. This work not only extends the dynamical range probed by standard isothermal XPCS, but also clarifies the fate of the alpha-relaxation across the glass transition and provides a new perception on the anomalous, compressed temporal decay of the density-density correlation functions observed in metallic glasses and many out-of-equilibrium soft materials.
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Submitted 22 March, 2024; v1 submitted 18 March, 2024;
originally announced March 2024.
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Denser glasses relax faster: a competition between rejuvenation and aging during in-situ high pressure compression at the atomic scale
Authors:
A. Cornet,
G. Garbarino,
F. Zontone,
Y. Chushkin,
J. Jacobs,
E. Pineda,
T. Deschamps,
S. Li,
A. Ronca,
J. Shen,
G. Morard,
N. Neuber,
M. Frey,
R. Busch,
I. Gallino,
M. Mezouar,
G. Vaughan,
B. Ruta
Abstract:
A fascinating feature of metallic glasses is their ability to explore different configurations under mechanical deformations. This effect is usually observed through macroscopic observables, while little is known on the consequence of the deformation at atomic level. Using the new generation of synchrotrons, we probe the atomic motion and structure in a metallic glass under hydrostatic compression…
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A fascinating feature of metallic glasses is their ability to explore different configurations under mechanical deformations. This effect is usually observed through macroscopic observables, while little is known on the consequence of the deformation at atomic level. Using the new generation of synchrotrons, we probe the atomic motion and structure in a metallic glass under hydrostatic compression, from the onset of the perturbation up to a severely-compressed state. While the structure indicates reversible densification under compression, the dynamic is dramatically accelerated and exhibits a hysteresis with two regimes. At low pressures, the atomic motion is heterogeneous with avalanche-like rearrangements suggesting rejuvenation, while under further compression, aging leads to a super-diffusive dynamics triggered by internal stresses inherent to the glass. These results highlight the complexity of the atomic motion in non-ergodic systems and support a theory recently developed to describe the surprising rejuvenation and strain hardening of metallic glasses under compression.
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Submitted 6 January, 2023;
originally announced January 2023.
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Disentangling structural and kinetic components of the α-relaxation in supercooled metallic liquids
Authors:
Nico Neuber,
Oliver Gross,
Maximilian Frey,
Benedikt Bochtler,
Alexander Kuball,
Simon Hechler,
Fan Yang,
Eloi Pineda,
Fabian Westermeier,
Michael Sprung,
Isabella Gallino,
Ralf Busch,
Beatrice Ruta
Abstract:
The particle motion associated to the α-relaxation in supercooled liquids is still challenging scientists due to its difficulty to be probed experimentally. By combining synchrotron techniques, we found the existence of microscopic structure-dynamics relationships in Pt42.5Cu27Ni9.5P21 and Pd42.5Cu27Ni9.5P21 liquids which allows us to disentangle structural and kinetic contributions to the α-proce…
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The particle motion associated to the α-relaxation in supercooled liquids is still challenging scientists due to its difficulty to be probed experimentally. By combining synchrotron techniques, we found the existence of microscopic structure-dynamics relationships in Pt42.5Cu27Ni9.5P21 and Pd42.5Cu27Ni9.5P21 liquids which allows us to disentangle structural and kinetic contributions to the α-process. While the two alloys show similar kinetic fragilities, their structural fragilities differ and correlate with the temperature dependence of the stretching parameter describing the decay of the density fluctuations. This implies that the evolution of dynamical heterogeneities in supercooled alloys is determined by the rigidity of the melt structure. We find also that the atomic motion not only reflects the topological order but also the chemical short-range order, which can lead to a surprising slowdown of the α-process at the mesoscopic length scale. These results will contribute to the comprehension of the glass transition, which is still missing.
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Submitted 20 September, 2022;
originally announced September 2022.
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Wave vector dependence of the dynamics in supercooled metallic liquids
Authors:
B. Ruta,
S. Hechler,
N. Neuber,
D. Orsi,
L. Cristofolini,
O. Gross,
B. Bochtler,
M. Frey,
A. Kuball,
S. S. Riegler,
M. Stolpe,
Z. Evenson,
C. Gutt,
F. Westermeier,
R. Busch,
I. Gallino
Abstract:
We present a detailed investigation of the wave vector dependence of collective atomic motion in Au49Cu26.9Si16.3Ag5.5Pd2.3 and Pd42.5Cu27Ni9.5P21 supercooled liquids close to the glass transition temperature. Using x-ray photon correlation spectroscopy in a precedent uncovered spatial range of only few interatomic distances, we show that the microscopic structural relaxation process follows in ph…
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We present a detailed investigation of the wave vector dependence of collective atomic motion in Au49Cu26.9Si16.3Ag5.5Pd2.3 and Pd42.5Cu27Ni9.5P21 supercooled liquids close to the glass transition temperature. Using x-ray photon correlation spectroscopy in a precedent uncovered spatial range of only few interatomic distances, we show that the microscopic structural relaxation process follows in phase the structure with a marked slowing down at the main average inter-particle distance. This behavior is accompanied by dramatic changes in the shape of the intermediate scattering functions which suggest the presence of large dynamical heterogeneities at length-scales corresponding to few particle diameters. A ballistic-like mechanism of particle motion seems to govern the structural relaxation of the two systems in the highly viscous phase, likely associated to hopping of caged particles in agreement with theoretical studies.
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Submitted 28 August, 2020; v1 submitted 3 March, 2020;
originally announced March 2020.
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Application of optimal band-limited control protocols to quantum noise sensing
Authors:
V. M. Frey,
S. Mavadia,
L. M. Norris,
W. de Ferranti,
D. Lucarelli,
L. Viola,
M. J. Biercuk
Abstract:
Industrial, metrological, and medical applications provide a strong technological pull for advanced nanoscale sensors exploiting the unique sensitivity of quantum coherent systems to their environments. Essential to the functionality of these devices is the availability of control protocols which shape the sensor's response to the environment in frequency space. However, a key challenge in these a…
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Industrial, metrological, and medical applications provide a strong technological pull for advanced nanoscale sensors exploiting the unique sensitivity of quantum coherent systems to their environments. Essential to the functionality of these devices is the availability of control protocols which shape the sensor's response to the environment in frequency space. However, a key challenge in these applications is that common control routines result in out-of-band spectral leakage which complicates interpretation of the sensor's signal. In this work we demonstrate provably optimal narrowband control protocols ideally suited to quantum sensing. Our results, based on experiments with trapped ions using modulation in the form of discrete prolate spheroidal sequences (aka Slepian functions), demonstrate reduction of spectral leakage by orders of magnitude over conventional controls. We tune the narrowband sensitivity using concepts from RF engineering and experimentally reconstruct complex noise spectra using engineered noise for quantitative performance evaluation. We then deploy these techniques to identify previously immeasurable frequency-resolved amplitude noise in our qubit synthesis chain with calibrated sensitivity better than 0.001 dB.
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Submitted 6 April, 2017;
originally announced April 2017.
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Current Noise in Tunnel Junctions
Authors:
Moritz Frey,
Hermann Grabert
Abstract:
We study current fluctuations in tunnel junctions driven by a voltage source. The voltage is applied to the tunneling element via an impedance providing an electromagnetic environment of the junction. We use circuit theory to relate the fluctuations of the current flowing in the leads of the junction with the voltage fluctuations generated by the environmental impedance and the fluctuations of the…
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We study current fluctuations in tunnel junctions driven by a voltage source. The voltage is applied to the tunneling element via an impedance providing an electromagnetic environment of the junction. We use circuit theory to relate the fluctuations of the current flowing in the leads of the junction with the voltage fluctuations generated by the environmental impedance and the fluctuations of the tunneling current. The spectrum of current fluctuations is found to consist of three parts: a term arising from the environmental Johnson-Nyquist noise, a term due to the shot noise of the tunneling current and a third term describing the cross-correlation between these two noise sources. Our phenomenological theory reproduces previous results based on the Hamiltonian model for the dynamical Coulomb blockade and provides a simple understanding of the current fluctuation spectrum in terms of circuit theory and properties of the average current. Specific results are given for a tunnel junction driven through a resonator.
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Submitted 13 July, 2016;
originally announced July 2016.
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Effect of the electromagnetic environment on current fluctuations in driven tunnel junctions
Authors:
Moritz Frey,
Hermann Grabert
Abstract:
We examine current fluctuations in tunnel junctions driven by a superposition of a constant and a sinusoidal voltage source. In standard setups the external voltage is applied to the tunneling element via an impedance providing an electromagnetic environment of the junction. The modes of this environment are excited by the time-dependent voltage and are the source of Johnson-Nyquist noise. We dete…
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We examine current fluctuations in tunnel junctions driven by a superposition of a constant and a sinusoidal voltage source. In standard setups the external voltage is applied to the tunneling element via an impedance providing an electromagnetic environment of the junction. The modes of this environment are excited by the time-dependent voltage and are the source of Johnson-Nyquist noise. We determine the autocorrelation function of the current flowing in the leads of the junction in the weak tunneling limit up to terms of second order in the tunneling Hamiltonian. The driven modes of the electromagnetic environment are treated exactly by means of a unitary transformation introduced recently. Particular emphasis is placed on the spectral function of the current fluctuations. The spectrum is found to comprise three contributions: a term arising from the Johnson-Nyquist noise of the environmental impedance, a part due to the shot noise of the tunneling element and a third contribution which comes from the cross-correlation between fluctuations caused by the electromagnetic environment and fluctuations of the tunneling current. All three parts of the spectral function occur already for devices under dc bias. The spectral function of ac driven tunneling elements can be determined from the result for a dc bias by means of a photo-assisted tunneling relation of the Tien-Gordon type. Specific results are given for an Ohmic environment and for a junction driven through a resonator.
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Submitted 25 July, 2016; v1 submitted 29 February, 2016;
originally announced February 2016.
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Strong Local Passivity in Finite Quantum Systems
Authors:
Michael Frey,
Ken Funo,
Masahiro Hotta
Abstract:
Passive states of quantum systems are states from which no system energy can be extracted by any cyclic (unitary) process. Gibbs states of all temperatures are passive. Strong local (SL) passive states are defined to allow any general quantum operation, but the operation is required to be local, being applied only to a specific subsystem. Any mixture of eigenstates in a system-dependent neighborho…
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Passive states of quantum systems are states from which no system energy can be extracted by any cyclic (unitary) process. Gibbs states of all temperatures are passive. Strong local (SL) passive states are defined to allow any general quantum operation, but the operation is required to be local, being applied only to a specific subsystem. Any mixture of eigenstates in a system-dependent neighborhood of a nondegenerate, entangled ground state is found to be SL passive. In particular, Gibbs states are SL passive with respect to a subsystem only at or below a critical, system-dependent temperature. SL passivity is associated in many-body systems with the presence of ground state entanglement in a way suggestive of collective quantum phenomena such as quantum phase transitions, superconductivity, and the quantum Hall effect. The presence of SL passivity is detailed for some simple spin systems where it is found that SL passivity is neither confined to systems of just a few particles nor limited to the near vicinity of the ground state.
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Submitted 1 August, 2014; v1 submitted 20 April, 2014;
originally announced April 2014.