Electronic Transport and Magnetic Properties of CrTe Epitaxial Thin Films with Room Temperature Ferromagnetism

Abstract In this paper, we report the electronic transport and room-temperature ferromagnetism with Curie temperature ~ 330 K in 25-nm NiAs-type CrTe thin films epitaxially grown on SrTiO₃ (111) substrates using molecular beam epitaxy. Upon cooling from 350 K, the CrTe film undergoes paramagnetic-to-ferromagnetic (PM-to-FM) and ferromagnetic-to-antiferromagnetic (AFM) phase transitions. In the ground state (2 K), the spins basically form antiferromagnetic ordering between Cr1 and Cr2 layers, however, still with a weak remanent magnetization of 123 emu/cc (~ 0.23 µB/f.u.), implying slight spin canting within Cr sub-lattice direction. For the 100, 500, and 1000 Oe magnetic field, the field-cooled in-plane remanent magnetization at 2 K exceeds the field-cooled out-of-plane one by factors of 42, 12.4, and 14.8, respectively, indicating strong magnetic anisotropy. Associated with the PM-to-FM phase transition, the CrTe film shows an insulator-to-metal electronic phase transition and negative magnetoresistance, which can be qualitatively understood within the framework of the electronic phase separation model.