  Exploring new magnetic materials is essential for finding advantageous
functional properties such as magnetoresistance, magnetocaloric effect,
spintronic functionality, and multiferroicity. Versatile classes of double
perovskite compounds have been recently investigated because of intriguing
physical properties arising from the proper combination of several magnetic
ions. In this study, it is observed that the dominant ferrimagnetic phase is
coexisted with a minor multiferroic phase in single-crystalline
double-perovskite Er2CoMnO6. The majority portion of the ferrimagnetic order is
activated by the long-range order of Er3+ moments below TEr = 10 K in addition
to the ferromagnetic order of Co2+ and Mn4+ moments arising at TC = 67 K,
characterized by compensated magnetization at TComp = 3.15 K. The inverted
magnetic hysteresis loop observed below TComp can be described by an extended
Stoner-Wohlfarth model. The additional multiferroic phase is identified by the
ferroelectric polarization of 0.9 uC/m2 at 2 K. The coexisting ferrimagnetic
and multiferroic phases appear to be strongly correlated in that metamagnetic
and ferroelectric transitions occur simultaneously. The results based on
intricate magnetic correlations and phases in Er2CoMnO6 enrich fundamental and
applied research on magnetic materials through the scope of distinct magnetic
characteristics in double perovskites.
