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Disorder mediated fully compensated ferrimagnetic spin-gapless semiconducting behaviour in Cr3Al Heusler alloy
Authors:
Reshna Elsa Philip,
Pooja Vyas,
Nikhil Joseph Joy,
Sandip Kumar Kuila,
Sonia Beniwal,
Akshata Magar,
Dinesh Kumar Shukla,
Partha Pratim Jana,
Amit Kumar,
Aftab Alam,
Jayakumar Balakrishnan,
Soham Manni
Abstract:
Spin-gapless semiconductors (SGSs) that simultaneously host fully compensated ferrimagnetism are highly sought for energy-efficient and stray-field-free spintronic technologies, yet their realization in chemically disordered systems has remained elusive. Here, we demonstrate that the binary Heusler alloy Cr3Al despite adopting a fully A2-disordered structure exhibits a rare coexistence of SGS tran…
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Spin-gapless semiconductors (SGSs) that simultaneously host fully compensated ferrimagnetism are highly sought for energy-efficient and stray-field-free spintronic technologies, yet their realization in chemically disordered systems has remained elusive. Here, we demonstrate that the binary Heusler alloy Cr3Al despite adopting a fully A2-disordered structure exhibits a rare coexistence of SGS transport and a fully compensated ferrimagnetic (FCF) ground state. Single-crystalline and polycrystalline Cr3Al samples were synthesized, and comprehensive structural analyses using single crystal XRD, synchrotron powder XRD, and neutron powder diffraction reveal complete Cr/Al site mixing. Remarkably, this chemical disorder does not disrupt magnetic order; instead, magnetization, X-ray magnetic circular dichroism (XMCD), and temperature-dependent neutron diffraction establish a robust compensated ferrimagnetic state with a vanishingly small ordered moment of 0.1(1) muB/f.u and a high Curie temperature of 773(2) K. Electrical and thermal transport measurements uncover clear SGS characteristics, including weak temperature-dependent conductivity, very low Seebeck coefficients, and electron-hole compensated transport. Hall measurements show unusual temperature-dependent carrier concentrations consistent with disorder-modified electronic states. First-principles calculations on an A2-disordered SQS structure reproduce the experimentally observed negligibly small magnetization (0.0072 muB/f.u) and reveal a vanishing spin-up band gap unambiguously supporting SGS behavior driven by chemical disorder. Our results identify Cr3Al as the first experimentally verified A2-disordered Heusler alloy exhibiting both fully compensated ferrimagnetism and spin-gapless semiconducting transport, positioning it as a robust and disorder-tolerant platform for next-generation, high-temperature spintronic devices.
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Submitted 11 December, 2025;
originally announced December 2025.
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Investigation of competing magnetic orders and the associated spin-phonon coupling effect in quasi-2D Cr1+xTe2 (x = 0.22) single crystal
Authors:
Gayathri V,
Sathishkumar M,
Sandip Kumar Kuila,
Vikash Kumar,
Abhidev B,
Reshna Elsa Philip,
Partha Pratim Jana,
Soham Manni
Abstract:
Single crystals of quasi-2D chromium telluride system represented by Cr1+xTe2 (x = 0.22), which crystallizes in the trigonal structure with the c-axis as the growth direction, are synthesized by the flux method. The magnetization measurements revealed the coexistence and competition between ferromagnetic and antiferromagnetic exchange interactions due to the presence of the intercalated Cr-layers.…
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Single crystals of quasi-2D chromium telluride system represented by Cr1+xTe2 (x = 0.22), which crystallizes in the trigonal structure with the c-axis as the growth direction, are synthesized by the flux method. The magnetization measurements revealed the coexistence and competition between ferromagnetic and antiferromagnetic exchange interactions due to the presence of the intercalated Cr-layers. A series of diverse magnetic transitions is exhibited by the crystal. While cooling the crystal, it undergoes a paramagnetic to antiferromagnetic transition at 190 K, followed by a transition into a ferromagnetic state at around 160 K, and a spin-canting at a lower temperature of 75 K. A possible lack of inversion symmetry in the crystal structure, along with the observance of an unusual jump and loop opening in the isothermal magnetization suggests that the crystals Cr1+xTe2 (x = 0.22) may host skyrmions. Furthermore, concomitant to their magnetic transitions, anomalies were observed in the derived Breit-Wigner-Fano fit parameters obtained from the asymmetric temperature-dependent Raman spectra, evidencing a strong spin-phonon coupling effect, intrinsic to the grown crystals. A strong perpendicular magnetic anisotropy along with the robust spin-phonon coupling, makes the system a promising candidate for prospective spintronics applications.
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Submitted 18 July, 2025;
originally announced July 2025.
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Unveiling the interplay of magnetic order and electronic band structure on the evolution of anomalous Hall effect in MnPtGa single crystal
Authors:
Gourav Dwari,
Shovan Dan,
Bishal Baran Maity,
Sitaram Ramakrishnan,
Achintya Lakshan,
Ruta Kulkarni,
Vikash Sharma,
Suman Nandi,
Partha Pratim Jana,
Andrzej Ptok,
A. Thamizhavel
Abstract:
The recent studies on the anomalous Hall effect (AHE) have revealed an intrinsic relationship between the topological band structure and the experimentally observed transverse conductivity. Consequently, this has led to a heightened focus on examining the topological aspects of AHE. Here we have studied sign reversal of anomalous Hall conductivity with temperature in the single crystalline MnPtGa…
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The recent studies on the anomalous Hall effect (AHE) have revealed an intrinsic relationship between the topological band structure and the experimentally observed transverse conductivity. Consequently, this has led to a heightened focus on examining the topological aspects of AHE. Here we have studied sign reversal of anomalous Hall conductivity with temperature in the single crystalline MnPtGa (space group: $P6_3/mmc$). From the interdependence of the linear resistance, we claim that the origin of such behavior is intrinsic. By systematically studying the electronic band structure and Berry curvature of MnPtGa using first principle calculations supported by magnetic susceptibility and isothermal magnetization measurements we demonstrate that the temperature dependent complex magnetic structure plays a significant role and leads to the sign reversal of anomalous Hall conductivity. We proposed a continuous evolution of the magnetic structure, supported by the ab initio calculations, which is consistent with the experimental data. Our studies have established that the critical temperature ($\approx$110 K), where the sign reversal appears is associated with the magnetic structure and the magnitude of Mn moments.
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Submitted 3 May, 2025;
originally announced May 2025.
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Accessing quasi-flat $\textit{f}$-bands to harvest large Berry curvature in NdGaSi
Authors:
Anyesh Saraswati,
Jyotirmoy Sau,
Vera Misheneva,
Rui Lou,
Sudipta Chatterjee,
Sandip Kumar Kuila,
Bibhas Ghanta,
Anup Kumar Bera,
Partha Pratim Jana,
Alexander Fedorov,
Setti Thirupathaiah,
Manoranjan Kumar,
Nitesh Kumar
Abstract:
In typical rare-earth lanthanide compounds, the localized 4\textit{f}-electrons have a weak effect on the electrical conduction, limiting their influence on the Berry curvature and, hence, the intrinsic anomalous Hall effect. A comprehensive study of the magnetic, thermodynamic, and transport properties of single-crystalline NdGaSi, guided by first-principles calculations, reveals a ferromagnetic…
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In typical rare-earth lanthanide compounds, the localized 4\textit{f}-electrons have a weak effect on the electrical conduction, limiting their influence on the Berry curvature and, hence, the intrinsic anomalous Hall effect. A comprehensive study of the magnetic, thermodynamic, and transport properties of single-crystalline NdGaSi, guided by first-principles calculations, reveals a ferromagnetic ground state that induces a splitting of quasi-flat 4\textit{f} electronic bands and positions them near the Fermi energy. The observation of an extraordinarily large intrinsic anomalous Hall conductivity of 1165 $Ω^{-1}$ cm$^{-1}$ implies the direct involvement of localized states in the generation of non-trivial band crossings around the Fermi energy. The angle-resolved photoemission spectroscopy measurements provide direct evidence of non-trivial crossing of the 4\textit{f}-bands with dispersive bands. These results are remarkable when compared to ferrimagnetic NdAlSi, which differs only in a non-magnetic atom (a change in the principal quantum number \textit{n} of the outer \textit{p }orbital) with the same number of valence electrons and does not exhibit any measurable anomalous Hall conductivity.
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Submitted 2 April, 2026; v1 submitted 17 April, 2025;
originally announced April 2025.
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Peculiar magnetic and magneto-transport properties in a non-centrosymmetric self-intercalated van der Waals ferromagnet Cr5Te8
Authors:
Banik Rai,
Sandip Kumar Kuila,
Rana Saha,
Sankalpa Hazra,
Chandan De,
Jyotirmoy Sau,
Venkatraman Gopalan,
Partha Pratim Jana,
Stuart S. P. Parkin,
Nitesh Kumar
Abstract:
Trigonal Cr$_5$Te$_8$, a self-intercalated van der Waals ferromagnet with an out-of-plane magnetic anisotropy, has long been known to crystallize in a centrosymmetric structure. However, optical second harmonic generation experiments, together with comprehensive structural analysis, indicate that this compound rather adopts a non-centrosymmetric structure. Lorentz transmission electron microscopy…
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Trigonal Cr$_5$Te$_8$, a self-intercalated van der Waals ferromagnet with an out-of-plane magnetic anisotropy, has long been known to crystallize in a centrosymmetric structure. However, optical second harmonic generation experiments, together with comprehensive structural analysis, indicate that this compound rather adopts a non-centrosymmetric structure. Lorentz transmission electron microscopy reveals the presence of Néel-type skyrmions, consistent with its non-centrosymmetric structure. A large anomalous Hall conductivity of 102 ohm$^{-1}$cm$^{-1}$ at low temperature stems from intrinsic origin, which is larger than any previously reported values in the bulk Cr-Te system. Notably, spontaneous topological Hall resistivity arising from the skyrmionic phase has been observed. Our findings not only elucidate the unique magnetic and magneto-transport properties of non-centrosymmetric trigonal Cr$_5$Te$_8$, but also open new avenues for investigating the effects of broken inversion symmetry on material properties and their potential applications.
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Submitted 4 February, 2025; v1 submitted 4 April, 2024;
originally announced April 2024.