Thermodynamics, elastic anomalies and excitations in the field induced phases of CeRh2As2

TL;DR

This paper investigates the thermodynamic and elastic anomalies in CeRh2As2, revealing how magnetic and quadrupolar orders influence phase transitions and excitations under magnetic fields.

Contribution

It provides a detailed theoretical analysis of thermodynamic, elastic, and magnetic response functions in CeRh2As2, highlighting the role of quadrupolar order and excitations across phases.

Findings

Identification of thermodynamic anomalies associated with phase boundaries.

Calculation of elastic constant anomalies influenced by quadrupolar order.

Analysis of magnetic susceptibility and low-energy magnetic mode dispersion.

Abstract

The tetragonal heavy fermion compound CeRh2As2 exhibits unconventional superconductivity accompanied by other broken symmetry phases that have been identified as presumably small moment intrinsic antiferromagnetism at low magnetic fields and induced quadrupolar order at higher in-plane fields. The latter may extend to very large pulsed-field range. The phase boundaries can be investigated by following thermodynamic anomalies like specific heat, magnetocaloric coefficient, thermal expansion and magnetostriction. We calculate their discontinuities and identify the influence of the field induced quadrupole on them. Furthermore we investigate the elastic constant anomalies which are determined by the static homogeneous quadrupolar RPA response functions. We present a calculation of these anomalies for the appropriate symmetry mode both in the disordered and ordered regime and investigate their change with applied field. In addition we consider the dynamical momentum dependent magnetic susceptibility and the associated dispersion of low energy magnetic modes and how their characteristics change across the phase boundary.