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Superconductivity and Charge-density-wave-like Transition in Th2Cu4As5
Authors:
Qing-Chen Duan,
Shao-Hua Liu,
Bai-Zhuo Li,
Jiao-Jiao Meng,
Wu-Zhang Yang,
Yi Liu,
Yi-Qiang Lin,
Si-Qi Wu,
Jia-Yi Lu,
Jin-Ke Bao,
Yu-Sen Xiao,
Xin-Yu Zhao,
Yu-Xue Mei,
Yu-Ping Sun,
Dan Yu,
Shu-Gang Tan,
Qiang Jing,
Rui-Dan Zhong,
Yong-Liang Chen,
Yong Zhao,
Zhi Ren,
Cao Wang,
Guang-Han Cao
Abstract:
We report the synthesis, crystal structure, and physical properties of a novel ternary compound, Th$_2$Cu$_4$As$_5$. The material crystallizes in a tetragonal structure with lattice parameters $a=4.0716(1)$ Å and $c=24.8131(4)$ Å. Its structure can be described as an alternating stacking of fluorite-type Th$_2$As$_2$ layers with antifluorite-type double-layered Cu$_4$As$_3$ slabs. The measurement…
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We report the synthesis, crystal structure, and physical properties of a novel ternary compound, Th$_2$Cu$_4$As$_5$. The material crystallizes in a tetragonal structure with lattice parameters $a=4.0716(1)$ Å and $c=24.8131(4)$ Å. Its structure can be described as an alternating stacking of fluorite-type Th$_2$As$_2$ layers with antifluorite-type double-layered Cu$_4$As$_3$ slabs. The measurement of electrical resistivity, magnetic susceptibility and specific heat reveals that Th$_2$Cu$_4$As$_5$ undergoes bulk superconducting transition at 4.2 K. Moreover, all these physical quantities exhibit anomalies at 48 K, where the Hall coefficient change the sign. These findings suggest a charge-density-wave-like (CDW) transition, making Th$_2$Cu$_4$As$_5$ a rare example for studying the interplay between CDW and superconductivity.
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Submitted 22 November, 2023;
originally announced November 2023.
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Evidence for mechanical softening-hardening dual anomaly in transition metals from shock compressed vanadium
Authors:
Hao Wang,
J. Li,
X. M. Zhou,
Y. Tan,
L. Hao,
Y. Y. Yu,
C. D. Dai,
K. Jin,
Q. Wu,
Q. M. Jing,
X. R. Chen,
X. Z. Yan,
Y. X. Wang,
Hua Y. Geng
Abstract:
Solid usually becomes harder and tougher under compression, and turns softer at elevated temperature. Recently, compression-induced softening and heating-induced hardening (CISHIH) dual anomaly was predicted in group VB elements such as vanadium. Here, the evidence for this counterintuitive phenomenon is reported. By using accurate high-temperature high-pressure sound velocities measured at Hugoni…
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Solid usually becomes harder and tougher under compression, and turns softer at elevated temperature. Recently, compression-induced softening and heating-induced hardening (CISHIH) dual anomaly was predicted in group VB elements such as vanadium. Here, the evidence for this counterintuitive phenomenon is reported. By using accurate high-temperature high-pressure sound velocities measured at Hugoniot states generated by shock-waves, together with first-principles calculations, we observe not only the prominent compression-induced sound velocity reduction, but also strong heating-induced sound velocity enhancement, in shocked vanadium. The former corresponds to the softening in shear modulus by compression, whereas the latter reflects the reverse hardening by heat. These experiments also unveil another anomaly in Young's modulus that wasn't reported before. Based on the experimental and theoretical data, we infer that vanadium might transition from BCC into two different rhombohedral (RH1 and RH2) phases at about 79GPa and 116GPa along the Hugoniot, respectively, which implies a dramatic difference in static and dynamic loading, as well as the significance of deviatoric stress and rate-relevant effects in high-pressure phase transition dynamics.
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Submitted 31 January, 2022;
originally announced January 2022.
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Coexistence of Ferroelectric-like Polarization and Dirac-like Surface State in TaNiTe5
Authors:
Yunlong Li,
Zhao Ran,
Chaozhi Huang,
Guanyong Wang,
Peiyue Shen,
Haili Huang,
Chunqiang Xu,
Yi Liu,
Wenhe Jiao,
Wenxiang Jiang,
Jiayuan Hu,
Gucheng Zhu,
Chenhang Xu,
Qi Lu,
Guohua Wang,
Qiang Jing,
Shiyong Wang,
Zhiwen Shi,
Jinfeng Jia,
Xiaofeng Xu,
Wentao Zhang,
Weidong Luo,
Dong Qian
Abstract:
By combining angle-resolved photoemission spectroscopy (ARPES), scanning tunneling microscopy (STM), piezoresponse force microscopy (PFM) and first-principles calculations, we have studied the low-energy band structure, atomic structure and charge polarization on the surface of a topological semimetal candidate TaNiTe5. Dirac-like surface states were observed on the (010) surface by ARPES, consist…
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By combining angle-resolved photoemission spectroscopy (ARPES), scanning tunneling microscopy (STM), piezoresponse force microscopy (PFM) and first-principles calculations, we have studied the low-energy band structure, atomic structure and charge polarization on the surface of a topological semimetal candidate TaNiTe5. Dirac-like surface states were observed on the (010) surface by ARPES, consistent with the first-principles calculations. On the other hand, PFM reveals a switchable ferroelectric-like polarization on the same surface. We propose that the noncentrosymmetric surface reconstruction observed by STM could be the origin of the observed ferroelectric-like state in this novel material. Our findings provide a new platform with the coexistence of ferroelectric-like surface charge distribution and novel surface states.
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Submitted 17 June, 2021;
originally announced June 2021.
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Superconductivity in ThMo2Si2C with Mo2C Square Net
Authors:
Zichen Liu,
Baizhuo Li,
Yusen Xiao,
Qingchen Duan,
Yanwei Cui,
YuXue Mei,
Qian Tao,
Shuli Wei,
Shugang Tan,
Qiang Jing,
Qing Lu,
Yuping Sun,
Yunyan Liu,
Shenggui Fu,
Hao Jiang,
Zhi Ren,
Zhu'an Xu,
Cao Wang,
Guanghan Cao
Abstract:
We report the superconductivity of a new quaternary compound ThMo$_2$Si$_2$C, synthesized with the arc-melting technique. The compound crystallizes in a tetragonal CeCr$_2$Si$_2$C-type structure with cell parameters of $a$ = 4.2296 Åand $c$ = 5.3571 Å. An interlayer Si-Si covalent bonding is suggested by the atomic distance. The electrical resistivity and magnetic susceptibility measurements indic…
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We report the superconductivity of a new quaternary compound ThMo$_2$Si$_2$C, synthesized with the arc-melting technique. The compound crystallizes in a tetragonal CeCr$_2$Si$_2$C-type structure with cell parameters of $a$ = 4.2296 Åand $c$ = 5.3571 Å. An interlayer Si-Si covalent bonding is suggested by the atomic distance. The electrical resistivity and magnetic susceptibility measurements indicate a Pauli-paramagnetic metal with dominant electron-electron scattering in the normal-state. Bulk superconductivity at 2.2 K is demonstrated with a dimensionless specific-heat jump of $ΔC/γ_{\rm n}T$ = 0.98. The superconducting parameters of the critical magnetic fields, coherence length, penetration depth, and superconducting energy gap are given.
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Submitted 20 April, 2021;
originally announced April 2021.
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Ultrasensitive Field-Effect Biosensors Enabled by the Unique Electronic Properties of Graphene
Authors:
Xiaoyan Zhang,
Qiushi Jing,
Shen Ao,
Grégory F. Schneider,
Dmitry Kireev,
Zhengjun Zhang,
Wangyang Fu
Abstract:
This review provides a critical overview of current developments on nanoelectronic biochemical sensors based on graphene. Composed of a single layer of conjugated carbon atoms, graphene has outstanding high carrier mobility and low intrinsic electrical noise, but a chemically inert surface. Surface functionalization is therefore crucial to unravel graphene sensitivity and selectivity for the detec…
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This review provides a critical overview of current developments on nanoelectronic biochemical sensors based on graphene. Composed of a single layer of conjugated carbon atoms, graphene has outstanding high carrier mobility and low intrinsic electrical noise, but a chemically inert surface. Surface functionalization is therefore crucial to unravel graphene sensitivity and selectivity for the detection of targeted analytes. To achieve optimal performance of graphene transistors for biochemical sensing, the tuning of the graphene surface properties via surface functionalization and passivation is highlighted, as well as the tuning of its electrical operation by utilizing multifrequency ambipolar configuration and a high frequency measurement scheme to overcome the Debye screening to achieve low noise and highly sensitive detection. Potential applications and prospectives of ultrasensitive graphene electronic biochemical sensors ranging from environmental monitoring and food safety, healthcare and medical diagnosis, to life science research, are presented as well.
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Submitted 10 December, 2020;
originally announced December 2020.
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Discovery of the Superconductivity in 3d Element Ni doped IrTe$_2$
Authors:
Qiang Jing,
Ping Li,
Yunze Long,
Jingfeng Wang,
Fei Jiao,
Xiaoxiong Wang,
Xiaomin Cui,
Wenxiang Jiang,
Guohua Wang,
Yunlong Li,
Gan Liu,
Cao Wang,
Bo Liu,
Dong Qian
Abstract:
IrTe$_2$ with large spin-orbital coupling (SOC) shows a CDW-like first order structural phase transition from high-temperature trigonal phase to low-temperature monoclinic phase at 270 K, accompanying with a large jump in transport and magnetic measurement as well as in heat capacity. Here, the 3d element Ni has been doped into IrTe$_2$ by growing Ir$_{1-x}$Ni$_x$Te$_2$ single crystals. Both XRD a…
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IrTe$_2$ with large spin-orbital coupling (SOC) shows a CDW-like first order structural phase transition from high-temperature trigonal phase to low-temperature monoclinic phase at 270 K, accompanying with a large jump in transport and magnetic measurement as well as in heat capacity. Here, the 3d element Ni has been doped into IrTe$_2$ by growing Ir$_{1-x}$Ni$_x$Te$_2$ single crystals. Both XRD and XPS results reveal that the Ni atoms have substituted for Ir, which is consistent with the calculation result. Like the CDW behaviour, the structural phase transition shows competition and coexistence with the superconductivity. The monoclinic phase transition has been suppressed gradually with the increase of the doping amount of Ni, at last giving rise to the stabilization of the trigonal phase with superconductivity. Within 0.1$\leq$x$\leq$0.2, Ir$_{1-x}$Ni$_x$Te$_2$ shows the superconductive behaviour with T$_c$ around 2.6K. The superconductivity shows anisotropy with dimensionless anisotropy parameter $γ$=$ξ_{//}$$/$$ξ_{\perp}$$\sim$ 2. Even Ni element shows ferromagnetic behaviour, Ir$_{1-x}$Ni$_x$Te$_2$ only shows weak paramagnetism, no ferromagnetic order is observed in it, which is coincident with the calculation result that their up and down spin density of states compensate each other well. In addition, for other 3d elements Fe, Co and Mn doped IrTe$_2$, only Ir$_{1-x}$Mn$_x$Te$_2$ owns magnetism with magnetic moment of 3.0$μ$$_B$ to the supercell, theoretically.
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Submitted 12 November, 2020;
originally announced November 2020.
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Electrical probing of COVID-19 spike protein receptor binding domain via a graphene field-effect transistor
Authors:
Xiaoyan Zhang,
Qige Qi,
Qiushi Jing,
Shen Ao,
Zhihong Zhang,
Mingchao Ding,
Muhong Wu,
Kaihui Liu,
Weipeng Wang,
Yunhan Ling,
Zhengjun Zhang,
Wangyang Fu
Abstract:
Here, in an effort towards facile and fast screening/diagnosis of novel coronavirus disease 2019 (COVID-19), we combined the unprecedently sensitive graphene field-effect transistor (Gr-FET) with highly selective antibody-antigen interaction to develop a coronavirus immunosensor. The Gr-FET immunosensors can rapidly identify (about 2 mins) and accurately capture the COVID-19 spike protein S1 (whic…
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Here, in an effort towards facile and fast screening/diagnosis of novel coronavirus disease 2019 (COVID-19), we combined the unprecedently sensitive graphene field-effect transistor (Gr-FET) with highly selective antibody-antigen interaction to develop a coronavirus immunosensor. The Gr-FET immunosensors can rapidly identify (about 2 mins) and accurately capture the COVID-19 spike protein S1 (which contains a receptor binding domain, RBD) at a limit of detection down to 0.2 pM, in a real-time and label-free manner. Further results ensure that the Gr-FET immunosensors can be promisingly applied to screen for high-affinity antibodies (with binding constant up to 2*10^11 M^-1 against the RBD) at concentrations down to 0.1 pM. Thus, our developed electrical Gr-FET immunosensors provide an appealing alternative to address the early screening/diagnosis as well as the analysis and rational design of neutralizing-antibody locking methods of this ongoing public health crisis.
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Submitted 27 March, 2020;
originally announced March 2020.
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The Layer-inserting Growth of Antiferromagnetic Topological Insulator MnBi$_2$Te$_4$ Based on Symmetry and Its X-ray Photoelectron Spectroscopy
Authors:
Fei Jiao,
Jingfeng Wang,
Xianyu Wang,
Meixia Chang,
Lingbo Cai,
Shu Zhu,
Di Zhang,
Qing Lu,
Cao Wang,
Shugang Tan,
Yunlong Li,
Jiayuan Hu,
Qiang Jing,
Bo Liu,
Dong Qian
Abstract:
The antiferromagnetic topological insulator has attracted lots of attention recently, as its intrinsic magnetism and topological property makes it a potential material to realize the quantum anomalous Hall effect (QAHE) at relative high temperature. Until now, only MnBi$_2$Te$_4$ is predicted and grown successfully. The other MB$_2$T$_4$-family materials predicted (MB$_2$T$_4$:M=transition-metal o…
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The antiferromagnetic topological insulator has attracted lots of attention recently, as its intrinsic magnetism and topological property makes it a potential material to realize the quantum anomalous Hall effect (QAHE) at relative high temperature. Until now, only MnBi$_2$Te$_4$ is predicted and grown successfully. The other MB$_2$T$_4$-family materials predicted (MB$_2$T$_4$:M=transition-metal or rare-earth element, B=Bi or Sb, T=Te, Se, or S) with not only antiferromagnetic topological property but also rich and exotic topological quantum states and dynamically stable (or metastable) structure have not been realized on experiment completely. Here, MnBi$_2$Te$_4$ single crystals have been grown successfully and tested. It shows typical antiferromagnetic character, with Neel temperature of 24.5K and a spin-flop transition at H$\thickapprox$35000 Oe, 1.8K. After obtaining MnBi$_2$Te$_4$ single crystals, we have tried to synthesize the other members of MB$_2$T$_4$-family materials, but things are not going so well. Then it inspires us to discuss the growth mechanism of MnBi$_2$Te$_4$. The growth mode may be the layer-inserting growth mode based on symmetry, which is supported by our X-ray photoelectron spectroscopy (XPS) measurement. The XPS measurement combing with the $Ar^+$ ion sputtering is done to investigate the chemical state of MnBi$_2$Te$_4$. Binding energies (BE) of the MnBi$_2$Te$_4$-related contributions to Mn2p and Te3d spectra agree well with those of inserting material $α$-MnTe. Rising intensity of the Mn2p satellite for divalent Mn (bound to chalcogen) with atomic number of ligand (from MnO to MnBi$_2$Te$_4$) has been observed, thus suggesting classification of MnBi$_2$Te$_4$ as the charge-transfer compound. Understanding the growth mode of MnBi$_2$Te$_4$ can help us to grow the other members of MB$_2$T$_4$-family materials.
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Submitted 3 November, 2020; v1 submitted 18 February, 2020;
originally announced February 2020.
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Peculiar Phase Diagram with Isolated Superconducting Regions in ThFeAsN$_{1-x}$O$_x$
Authors:
Bai-Zhuo Li,
Zhi-Cheng Wang,
Jia-Lu Wang,
Fu-Xiang Zhang,
Dong-Ze Wang,
Feng-Yuan Zhang,
Yu-Ping Sun,
Qiang Jing,
Hua-Fu Zhang,
Shu-Gang Tan,
Yu-Ke Li,
Chun-Mu Feng,
Yu-Xue Mei,
Cao Wang,
Guang-Han Cao
Abstract:
ThFeAsN$_{1-x}$O$_x$ ($0\leq x\leq0.6$) system with heavy electron doping has been studied by the measurements of X-ray diffraction, electrical resistivity, magnetic susceptibility and specific heat. The non-doped compound exhibits superconductivity at $T_\mathrm{c}^\mathrm{onset}=30$ K, which is possibly due to an internal uniaxial chemical pressure that is manifested by the extremely small value…
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ThFeAsN$_{1-x}$O$_x$ ($0\leq x\leq0.6$) system with heavy electron doping has been studied by the measurements of X-ray diffraction, electrical resistivity, magnetic susceptibility and specific heat. The non-doped compound exhibits superconductivity at $T_\mathrm{c}^\mathrm{onset}=30$ K, which is possibly due to an internal uniaxial chemical pressure that is manifested by the extremely small value of As height with respect to the Fe plane. With the oxygen substitution, the $T_\mathrm{c}$ value decreases rapidly to below 2 K for $0.1\leq x\leq0.2$, and surprisingly, superconductivity re-appears in the range of $0.25\leq x\leq0.5$ with a maximum $T_\mathrm{c}^\mathrm{onset}$ of 17.5 K at $x=0.3$. For the normal-state resistivity, while the samples in intermediate non-superconducting interval exhibit Fermi liquid behavior, those in other regions show a non-Fermi-liquid behavior. The specific heat jump for the superconducting sample of $x=0.4$ is $ΔC/(γT_\mathrm{c})=0.89$, which is discussed in terms of anisotropic superconducting gap. The peculiar phase diagram in ThFeAsN$_{1-x}$O$_x$ presents additional ingredients for understanding the superconducting mechanism in iron-based superconductors.
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Submitted 30 May, 2018;
originally announced May 2018.
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Localized electromechanical interactions in ferroelectric P(VDF-TrFE) nanowires investigated by scanning probe microscopy
Authors:
Yonatan Calahorra,
Richard A. Whiter,
Qingshen Jing,
Vijay Narayan,
Sohini Kar-Narayan
Abstract:
We investigate the electromechanical interactions in individual P(VDF-TrFE) nanowires in response to localized electrical poling via a conducting atomic force microscope tip. Spatially resolved measurements of piezoelectric coefficients and elastic moduli before and after poling reveal a striking dependence on the polarity of the poling field, notably absent in thin films of the same composition.…
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We investigate the electromechanical interactions in individual P(VDF-TrFE) nanowires in response to localized electrical poling via a conducting atomic force microscope tip. Spatially resolved measurements of piezoelectric coefficients and elastic moduli before and after poling reveal a striking dependence on the polarity of the poling field, notably absent in thin films of the same composition. These observations are attributed to the unclamped nature of the nanowires and the inherent asymmetry in their chemical and electrical interactions with the tip and underlying substrate. Our findings provide insights into the mechanism of poling/switching in polymer nanowires critical to ferroelectric device performance.
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Submitted 24 October, 2016;
originally announced October 2016.