Pressure-induced ferromagnetism in the topological semimetal EuCd$_2$As$_2$

Elena Gati; Sergey L. Bud'ko; Lin-Lin Wang; Adrian Valadkhani; Ritu Gupta; Brinda Kuthanazhi; Li Xiang; John M. Wilde; Aashish Sapkota; Zurab Guguchia; Rustem Khasanov; Roser Valenti; Paul C. Canfield

doi:10.1103/PhysRevB.104.155124

paper

Pressure-induced ferromagnetism in the topological semimetal EuCd $_{2}$ As $_{2}$

arXiv:2108.01871 · doi:10.1103/PhysRevB.104.155124

Abstract

The antiferromagnet and semimetal EuCd $_{2}$ As $_{2}$ has recently attracted a lot of attention due to a wealth of topological phases arising from the interplay of topology and magnetism. In particular, the presence of a single pair of Weyl points is predicted for a ferromagnetic configuration of Eu spins along the $c$ -axis in EuCd $_{2}$ As $_{2}$ . In the search for such phases, we investigate here the effects of hydrostatic pressure in EuCd $_{2}$ As $_{2}$ . For that, we present specific heat, transport and $μ$ SR measurements under hydrostatic pressure up to $\sim 2.5$ GPa, combined with {\it ab initio} density functional theory (DFT) calculations. Experimentally, we establish that the ground state of EuCd $_{2}$ As $_{2}$ changes from in-plane antiferromagnetic (AFM $_{ab}$ ) to ferromagnetic at a critical pressure of $\approx$ 2\,GPa, which is likely characterized by the moments dominantly lying within the $ab$ plane (FM $_{ab}$ ). The AFM $_{ab}$ -FM $_{ab}$ transition at such a relatively low pressure is supported by our DFT calculations. Furthermore, our experimental and theoretical results indicate that EuCd $_{2}$ As $_{2}$ moves closer to the sought-for FM $_{c}$ state (moments $∥$ $c$ ) with increasing pressure further. We predict that a pressure of $\approx$ \,23\,GPa will stabilize the FM $_{c}$ state, if Eu remains in a 2+ valence state. Thus, our work establishes hydrostatic pressure as a key tuning parameter that (i) allows for a continuous tuning between magnetic ground states in a single sample of EuCd $_{2}$ As $_{2}$ and (ii) enables the exploration of the interplay between magnetism and topology and thereby motivates a series of future experiments on this magnetic Weyl semimetal.

8 figures in main text, 6 figures in Appendix; 14 pages total

Pressure-induced ferromagnetism in the topological semimetal EuCd2​As2​

Abstract

References in corpus (11)

Pressure-induced ferromagnetism in the topological semimetal EuCd $_{2}$ As $_{2}$