Ferromagnetically correlated clusters in semimetallic Ru2NbAl Heusler alloy and its thermoelectric properties

Sanchayita Mondal, Chandan Mazumdar, R. Ranganathan, Eric Alleno, P. C. Sreeparvathy, V. Kanchana, and G. Vaitheeswaran
Phys. Rev. B 98, 205130 – Published 16 November 2018

Abstract

In this work, we report the structural, magnetic, electrical and thermal transport properties of the Heusler-type alloy Ru2NbAl. From the detailed analysis of magnetization data, we infer the presence of superparamagnetically interacting clusters with a Pauli paramagnetic background, while short-range ferromagnetic interaction is developed among the clusters below 5 K. The presence of this ferromagnetic interaction is confirmed through heat capacity measurements. The relatively small value of electronic contribution to specific heat γ (2.7mJmol1K2) as well as the linear nature of temperature dependence of the Seebeck coefficient indicate a semimetallic ground state with a pseudogap, which is also supported by our electronic structure calculations. The activated nature of resistivity is reflected in the observed negative temperature coefficient and has its origin in the charge carrier localization due to antisite defects, inferred from magnetic measurements as well as structural analysis. Although the absolute value of thermoelectric figure of merit is rather low (ZT=5.2×103) in Ru2NbAl, it is the largest among all the reported nondoped full Heusler alloys.

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  • Received 13 July 2018
  • Revised 7 September 2018

DOI:https://doi.org/10.1103/PhysRevB.98.205130

©2018 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Sanchayita Mondal1,2, Chandan Mazumdar2, R. Ranganathan2, Eric Alleno3, P. C. Sreeparvathy4, V. Kanchana4, and G. Vaitheeswaran5,6

  • 1Maharaja Manindra Chandra College, 20 Ramkanto Bose Street, Kolkata 700003, West Bengal, India
  • 2Condensed Matter Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064, India
  • 3Université Paris-Est, Institut de Chimie et des Matériaux Paris-Est, UMR 7182 CNRS UPEC, 2 rue H. Dunant, 94320 Thiais, France
  • 4Department of Physics, Indian Institute of Technology Hyderabad, Kandi, Medak 502285, Telangana, India
  • 5Advanced Centre of Research in High energy Materials (ACRHEM), University of Hyderabad, Prof. C. R. Rao Road, Gachibowli, Hyderabad 500046, Telangana, India
  • 6School of Physics, University of Hyderabad, Prof. C. R. Rao Road, Gachibowli, Hyderabad 500046, Telangana, India

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Issue

Vol. 98, Iss. 20 — 15 November 2018

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