Gd2Te3: an antiferromagnetic semimetal

I Panneer Muthuselvam; Raja Nehru; K Ramesh Babu; K Saranya; S N Kaul; Shen-Ming Chen; Wei-Tin Chen; Yanwen Liu; Guang-Yu Guo; Faxian Xiu; R Sankar

doi:10.1088/1361-648X/ab1570

Gd₂Te₃: an antiferromagnetic semimetal

J Phys Condens Matter. 2019 Jul 17;31(28):285802. doi: 10.1088/1361-648X/ab1570. Epub 2019 Apr 2.

Authors

I Panneer Muthuselvam¹, Raja Nehru, K Ramesh Babu, K Saranya, S N Kaul, Shen-Ming Chen, Wei-Tin Chen, Yanwen Liu, Guang-Yu Guo, Faxian Xiu, R Sankar

Affiliation

¹ Department of Physics, School of Basic and Applied Sciences, Central University of Tamil Nadu, Neelakudi, Thiruvarur 610005, Tamil Nadu, India. Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan, Republic of China. Institute of Physics, Academia Sinica, Taipei 10617, Taiwan, Republic of China.

PMID: 30939461
DOI: 10.1088/1361-648X/ab1570

Abstract

We report high-precision magnetization ([Formula: see text]), magnetic susceptibility ([Formula: see text]), specific heat (C _p(T, H)) and 'zero-field' electrical resistivity, [Formula: see text], data taken on Gd₂Te₃ single crystal over wide ranges of temperature and magnetic field (H), with either [Formula: see text]-axis or [Formula: see text]-plane. [Formula: see text] and [Formula: see text] unambiguously establish that the b-axis is the easy direction of magnetization whereas any direction in the ac-plane is a hard direction. The [Formula: see text]-type anomaly in 'zero-field' specific heat, C _p(T, H = 0), and an abrupt drop in [Formula: see text] (characteristic of the paramagnetic (PM) - antiferromagnetic (AFM) phase transition) are observed at the Néel temperature, [Formula: see text] K. [Formula: see text] and C _p(T,H) clearly demonstrate that [Formula: see text] shifts to lower temperatures with increasing H irrespective of whether H points in the easy or hard direction. When [Formula: see text], the [Formula: see text] isotherms at temperatures in the range 2.5 K [Formula: see text] [Formula: see text] K reveal the existence of a field-induced spin-flop (SF) transition at fields 4.0 T [Formula: see text] [Formula: see text] [Formula: see text] 4.5 T. The first principles electronic band structure and density of states calculations, based on the density functional theory, correctly predict an AFM ground state (stabilized primarily by the 4f Gd³⁺ - 5p Te^2-- 4f Gd³⁺ superexchange interactions) and the observed semi-metallic behavior for the Gd₂Te₃ compound. Moreover, these calculations yield the values [Formula: see text] [Formula: see text] for the ordered magnetic moment per Gd atom at T = 0, [Formula: see text] mJ mol^-1 K^-2 for the Sommerfeld coefficient for the electronic specific heat contribution and [Formula: see text] K for the Curie-Weiss temperature, respectively. These theoretical estimates conform well with the corresponding experimental values [Formula: see text] [Formula: see text], [Formula: see text] mJ mol^-1 K^-2 and [Formula: see text] K.