Influence of pressure on the magnetic behavior and the anomalous magnetoresistance in Tb₅Si₃

Abstract

The compound, Tb₅Si₃, crystallizing in Mn₅Si₃-type hexagonal structure, was recently reported by us to exhibit a sudden and huge enhancement in electrical resistivity ρ) at a critical magnetic field (H_cr) in the magnetically ordered state (< 70 K) tracking isothermal magnetization (M) behavior. We have investigated the influence of external pressure (≤15 kbar) and negative chemical pressure induced by Ge substitution for Si on M and ρ as a function of temperature (5-300 K) and magnetic field (< 120 kOe), with the primary aim of understanding the field-induced anomalies. Focusing on isothermal M and magnetoresistance (MR) at two temperatures, 5 and 20 K, we find that this ρ anomaly persists under external as well as negative chemical pressures, however, with a change in the H_cr. The pressure derivative of H_cr is negative and this trend and the MR behavior at the H_cr are comparable to that observed in some Laves phase itinerant magnetic systems. On the basis of this observation, we speculate that the magnetic fluctuations induced at this critical field could be responsible for the MR anomalies.