First-order nature of the spin-reorientation phase transition in SmCr O3

Abstract

© 2022 American Physical Society.The ever expected canted antiferromagnetic (CAFM) Pb′n′m:Γ4(Gx,Ay,FZ;FZR) to Pbn′m′:Γ2(Fx,Cy,GZ;FxR, CyR) spin reorientation phase transition (SRPT) has only recently been confirmed through high-resolution time-of-flight neutron scattering studies by Sau et al. [Phys. Rev. B 103, 144418 (2021)10.1103/PhysRevB.103.144418]. Despite several studies on SmCrO3, the nature of its SRPT still remains debatable. In the present study, we revisit the issue through dc M(T) and ac-susceptibility, χac(T), measurements. Repeated cycle field-cooled-cooling and field-cooled-warming dc M(T) measurements clearly expose a temperature point differentiating the regimes of continuous and discontinuous parts of the SRPT. The discontinuous part has a tiny but clear hysteresis in M(T), confirming the first-order nature of the SRPT with supercooling (T∗) and superheating (T∗∗) temperatures to be ∼33 and ∼36K, respectively. The hysteresis in the M(T) is strongly supported by the occurrence of hysteresis in the nondispersing peaks in χac(T), measured using a 3 Oe ac signal amplitude during cooling and heating under zero dc-bias. Below SRPT, the complete reversibility of M(T) and χac(T) confirms the second-order nature of the Sm3+ ordering at TN2, which arises due to independent Sm3+-Sm3+ interaction. Similarly, the absence of hysteresis in M(T) as well as in χac(T), across the paramagnetic to CAFM Γ4 phase transition, proves the second-order nature of this phase transition.