Structural distortion driven polaronic transport and table-like magnetocaloric properties in polycrystalline Tb0.7Sr0.3MnO3 compound

Abstract

This research mainly explores the structural, magnetic, magneto-transport, and magnetocaloric properties of the polycrystalline Tb_0.7Sr_0.3MnO₃ compound. The results reveal a significant modification of the compound's ground state with increasing the strength of the magnetic field. The strong distortion in the crystal structure highly controls the magnetic and magneto-transport properties of the system. Along with this, a prominent ‘table-like’ nature in the temperature-dependent magnetic entropy change has been noticed, showcasing the potential application of the compound in the field of Ericsson refrigeration technology. Notably, a substantial low-field magnetoresistance is noticed around T ∼ 60 K. The temperature dependent electrical resistivity data can be well explained with the help of polaronic transport conduction mechanisms namely small-polaron hopping and variable-range hopping models. Various significant parameters are calculated and the system possesses a non-adiabatic polaron hopping mechanism with a large electron–phonon coupling constant. This investigation contributes valuable insights into the intricate dynamics of the 3d–4f exchange interaction and crystallographic distortion, shedding light on the underlying mechanisms governing the magnetic and electrical transport properties of the Sr-doped TbMnO₃ compound.