Optical Investigations of YbCrO₃. II. Metamagnetic Transition in YbCrO₃

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R exciton lines of YbCrO₃ corresponding to the ⁴A_2g→²E_g transition of Cr³⁺ have been measured at 4.2 K, where a first order phase transition induced by magnetic field H₀(⁄⁄a)∼67 kOe has been found. We concluded that this phase transition is a metamagnetic transition at which the weak ferromagnetic moment of the Cr³⁺ spins reverses its coupling with the magnetic moment of the Yb³⁺ spins from antiparallel to parallel. By the analysis of the spectral changes in the metamagnetic transition, the molecular field upon the Cr³⁺ ion due to the Cr–Yb magnetic interaction was estimated. Generally, if the magnetic moment of the rare-earth spins couples antiparallel to the weak ferromagnetic moment of the transition-metal spins for other orthochromites and orthoferrites, the metamagnetic transition of this type will be expected.