Experimental evidence of magnetic training effect of electronic phase in Nd–Ca half-doped manganite

Abstract

Cooling and heating modes are shown to be able to significantly modify the magnetic and electrical properties of the half-doped perovskite manganite. The present paper reports on a precise investigation of this phenomenon (the so-called training effect) carried out on Nd0.5Ca0.5MnO3 manganite, which allow a fine tuning of the magnetic ground state. Refinement of the X-ray diffraction pattern shows that the synthesized sample is single phase and crystallizes in the orthorhombic structure with Pnma space group. Using magnetometry measurements, we have found that the sample is the seat of interesting phenomena like charge ordering, magnetic phase separation, spin-glass and inverse magnetocaloric effect. Magnetic-field-driven magnetization (M(μ0H)) measurements evidence the metamagnetic transition which not only depends on field value, but also on the thermal process (cooling or heating). Metamagnetic irreversibility in the magnetic field range (±5 T) and memory effect are observed at low temperatures due to the kinetic arrest phenomenon. It is worthwhile to mention that the coercive field increases with decreasing temperature and reaches 955 Oe at 20 K, which is sufficiently large compared with that one in the soft magnetic and makes the material quite interesting for spintronic applications. The electrical resistivity in a zero field was measured on both cooling and warming modes, and the data obtained were fitted by using different theoretical models. At low temperatures, the resistivity shows the presence of insulator-metal transition and is found to be in conformity with the magnetization data. A magnetic training effect due to the thermo-magnetic history dependent behavior is observed, where the resistivity is consistently irreversible.