Magnetoelastic Coupling and Phases in the Skyrmion Lattice Magnet Gd2PdSi3 Discovered by High-resolution Dilatometry

TL;DR

This study provides a comprehensive thermodynamic analysis of Gd2PdSi3, revealing magnetoelastic effects, detailed phase diagrams, and the influence of uniaxial pressure on skyrmion lattice phases using high-resolution dilatometry.

Contribution

It presents the first detailed thermodynamic characterization of the skyrmion lattice phase in Gd2PdSi3, including phase diagrams and pressure dependencies.

Findings

Magnetoelastic effects linked to antiferromagnetic order at TN1 and TN2.

Identification of a new feature at T* around 12 K.

Strong enhancement of skyrmion lattice phase under uniaxial pressure.

Abstract

We report detailed thermodynamic studies on high-quality single crystals of the centrosymmetric skyrmion-hosting intermetallic Gd2PdSi3 by means of high-resolution capacitance dilatometry in fields up to 15 T which are complemented by specific heat and magnetization studies. Our dilatometric measurements show magnetoelastic effects associated with antiferromagnetic order at TN1 = 22.3 K and TN2 = 19.7 K, as well as strong field effects in an applied magnetic field of 15 Tup to 200 K (150 K) for B||c (B||a*, i.e. B perp c). The data allow us to complete the magneticphase diagram, including a new feature at T* approx 12 K below which a new degree of freedom becomesrelevant. For the first time, the magnetic B vs. T phase diagram for the a*-axis is also reported. Gr\"uneisen analysis shows the onset of magnetic contributions around 60 K, i.e., well above TN1. Uniaxial pressure dependencies of opposite sign, -1.3 K/GPa and 0.3 K/GPa, are extracted for the out-of-plane and in-plane directions at TN1. For T* we obtain dT*/dpc= 1.4 K/GPa. In particular we elucidate thermodynamic properties of the recently discovered skyrmion lattice phase and show that it is strongly enhanced by uniaxial pressure.