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Samatham SS, Singh S, Shravan Kumar Reddy S, A SK, Yadam S, Babu PD, Takeuchi T, Suresh KG. Revealing magnetic and physical properties of TbFe 4.4Al 7.6: experiment and theory. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:205802. [PMID: 38328924 DOI: 10.1088/1361-648x/ad2719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 02/07/2024] [Indexed: 02/09/2024]
Abstract
We report on the magnetic, electrical transport, caloric and electronic structure properties of TbFe4.4Al7.6polycrystalline alloy using experiment and theory. The alloy crystallizes in tetragonal structure with I4/mmm space group with lattice parametersa = b= 8.7234(5) Å andc= 5.0387(6) Å. It is ferrimagnetic with a compensation temperature ofTcmp∼151 K, Curie-Weiss temperatureθCW∼172.11 K and an effective magnetic momentμeff= (2.37±0.07)μB/f.u withZ= 2. At low temperatures, kinetic arrest-like first-order phase transition is realized through the thermal hysteresis between field-cooled cooling and field-cooled warming curves ofM(T) and virgin curves ofM(H) andρ(H)which are outside the hysteresis loops with metamagnetic transition. The high magnetic field suppression of multiple transitions and reduced coercive fieldHcoerand remnant magnetizationMremwith increasing temperature are reported.HcoerandMremcease to exist above the compensation temperatureTcmp. A correlation between the isothermal magnetization and resistivity is discussed. Specific heatC(T) analysis reveals a Sommerfeld parameter ofγ= 0.098 J⋅mol-1⋅K-2and a Debye temperature ofθD∼351.2 K. The sample is metallic as inferred from theρ(T)behavior and Sommerfeld parameter. The magnetoresistance of the alloy is low and negative which indicates the suppression of weak spin-fluctuations. This alloy avoids the tricritical point despite first-to-second order phase transition. The electronic and magnetic structure calculations, by making use of full potential linearized augmented plane wave method, suggest metallic ferrimagnetic ground state of TbFe4.4Al7.6with Tb atoms contributing ferromagnetically (5.87μB) and Fe atoms with antiferromagnetic contribution (2.67μB), in close agreement with the experimental observation.
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Affiliation(s)
- S Shanmukharao Samatham
- Department of Physics, Chaitanya Bharathi Institute of Technology, Gandipet, Hyderabad 500 075, India
| | - Saurabh Singh
- Penn State University, University Park, PA 16802, United States of America
- Energy Materials Laboratory, Toyota Technological Institute, Hisakata Tempaku, Nagoya 468-8511, Japan
| | - S Shravan Kumar Reddy
- Department of Physics, Chaitanya Bharathi Institute of Technology, Gandipet, Hyderabad 500 075, India
| | - Santhosh Kumar A
- Department of Physics, Chaitanya Bharathi Institute of Technology, Gandipet, Hyderabad 500 075, India
| | - Sankararao Yadam
- Department of Physics, CVR College of Engineering, Ibrahimpatnam, Ranga Reddy, Telangana 501 510, India
| | - P D Babu
- UGC-DAE Consortium for Scientific Research, Mumbai Centre, BARC Campus, Mumbai 400 085, India
| | - Tsunehiro Takeuchi
- Energy Materials Laboratory, Toyota Technological Institute, Hisakata Tempaku, Nagoya 468-8511, Japan
| | - K G Suresh
- Magnetic Materials Laboratory, Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India
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Lima LS. Spin transport in non-Hermitian quantum systems. Sci Rep 2023; 13:11112. [PMID: 37430127 DOI: 10.1038/s41598-023-38293-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 07/06/2023] [Indexed: 07/12/2023] Open
Abstract
Transport in non-Hermitian quantum systems is studied. The goal is a better understanding of transport in non-Hermitian systems like the Lieb lattice due to its flat bands and the integrability of the Ising chain which allows transport in that model to be computed analytically. This is a very special feature that is not present in a generic non-Hermitian system. We obtain the behaviour of the spin conductivity as a function of the non-Hermitian parameters of each system with aim to verify the influence of variation them on conductivity. For all models analyzed: Ising model as well as noninteracting fermion models, we obtain a little influence of the non-Hermitian parameters on conductivity and thus, a small effect over transport coefficients. Furthermore, we obtain an influence of opening of the gap in the spectrum in these models on longitudinal conductivity as well.
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Affiliation(s)
- Leonardo S Lima
- Department of Physics, Federal Center for Technological Education of Minas Gerais, 30510-000, Belo Horizonte, MG, Brazil.
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