Switching magnetic spin-states using small magnetic fields in compositionally complex Sm(M7)O$_3$

Abstract

High-entropy perovskites (HEPs) offer a unique platform for exploring magnetic phenomena arising from extreme B-site chemical disorder. In Sm(M7)O$_3$, where there are 7 cations in equal amounts at the B-site; M = Ti, Cr, Mn, Fe, Co, Ni, Cu), we observe long-range antiferromagnetic ordering near 105 K accompanied by a small but robust excess magnetic moment intrinsic to the chemically disordered lattice. This uncompensated moment is evident from ZFC-FC irreversibility, shifts in the isothermal M(H) loops, and discrete remanent states identified through direct-current-demagnetization measurements. Remarkably, cooling fields as small as $\pm$ 20 Oe are sufficient to select the direction of the excess moment, and the chosen magnetic state remains stable against applied fields up to 50 kOe. A low-temperature anomaly in the remanent magnetization further reveals a secondary contribution from the Sm$^{3+}$ sublattice, although the primary origin of the excess moment resides in the B-site AFM sublattice.