Coexistence of large magnetoresistance and magnetocaloric effect in monovalent doped manganite La0.5Ca0.4Li0.1MnO3

Abstract

An investigation of the structural, transport, magnetic and magnetocaloric properties of polycrystalline La0.5Ca0.4Li0.1MnO3 is presented. A metal–insulatortransition occurs at 162K and shifts to higher temperatures under applied magnetic fields. It shows a large negative magnetoresisance (MR) effect (40% at 3T field) in a wide temperature range of 200K. Magnetic measurements and Arrott plot analysis reveal that the system undergoes a second order paramagnetic–ferromagnetic (PM–FM) phase transition at TC=250K. A large magnetocaloric effect (MCE) occurs in vicinity of the phase transition. The magnetic entropy change |ΔSM|max attains 4.16J/(kgK) under field change ∆H=3T and 2.11J/(kgK) under ∆H=1T. It possesses a large relative cooling power (RCP= 140J/kg) and a relatively wide temperature span (δTFWHM=34K) for ∆H=3T. By using the equation ΔSM(T,H)=−α∫0H[∂(lnρ)/∂T]HdH, we examine the relationship between the magnetic entropy change and the resistivity in the system and find a poor satisfiability of the relationship between them. This can be understood by the significant magnetoresistance originating from the electron tunneling between the FM domains.