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In this talk, I’ll discuss about the compound Tb5Si3, which exhibits a huge positive magneto-resistance (MR) at a critical field (Hcr) in the magnetically ordered state. Even under the influence of external pressure and negative chemical pressure, this anomaly persists, however with a change in Hcr. It is interpreted that the magnetic fluctuations due to “inverse metamagnetism phenomenon” is responsible for the observed MR anomalies. Further an unusual butterfly-shaped MR loop for the alloy Tb4LuSi3, in the magnetically ordered state is observed in the sense that the envelope curve lies above the virgin curve. Such an anomalous loop indicates unusual electronic phase separation, namely involving high resistive-high field phase and low resistive-virgin phase. Furthermore, investigation on some other Tb based compounds reveals that Tb5Si3 (and its derivatives) may not be unique in its MR anomaly and that there is a need to consider the concept of ‘inverse metamagnetism’ in general in antiferromagnetic systems.
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