Tuning colossal magnetoresistance response at roomtemperature by La2/3+ySr1/3−yMn1−yCryO3

The special formula of La2/3+ySr1/3−yMn1−yCryO3 with [Mn3+]/([Mn4+] + [Cr3+]) ratio fixed at optimal proportion 2:1 was designed to tune colossal magnetoresistance (CMR) response around room temperature and test the possibility of ferromagnetic (FM) interaction of hetero-ionic coupling between Mn3+ and Cr3+. The polycrystalline bulk samples were fabricated by the traditional solid-state reaction method. The structural, magnetic, electrical transports and magnetoresistance (MR) properties were investigated. An enhancement of CMR at room temperature with appropriate content y has been observed, meanwhile, substituting Cr for Mn in manganites shows inefficiency in lowering ferromagnetic-paramagnetic (FM-PM) transition temperature Tc and metal-insulator (M-I) transition temperature Tp. Experimental results indicate that there might exist a FM coupling between Mn3+ and Cr3+.