title: Magnetic and structural phase transitions of MnBi under high magnetic fields.
abstract: High-field x-ray diffraction and magnetization measurements and differential thermal analysis (DTA) were carried out for polycrystalline MnBi with an NiAs-type hexagonal structure to investigate its magnetic and structural phase transitions. The lattice parameterarapidly decreases below the spin reorientation temperatureTSR(=90 K) in a zero magnetic field. The parametercdecreases gradually with decreasing temperature and exhibits an anomaly in the vicinity ofTSR. By applying a magnetic field of 5 T, the parameteraincreases by ∼0.05% whenT<TSRand varies smoothly when 8≤T≤300 K. DTA data show that the magnetic phase transition temperature from the ferromagnetic state to the paramagnetic state increases linearly at a rate of 2 KT-1with increasing magnetic field up to 14 T.
authors.affiliation: High Field Laboratory for Superconducting Materials, Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Koyama
authors.affiliation: High Field Laboratory for Superconducting Materials, Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
authors.forename: Yoshifuru
authors.initials: Y
authors.lastname: Mitsui
authors.affiliation: High Field Laboratory for Superconducting Materials, Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Watanabe
keywords: MnBi; differential thermal analysis; high magnetic fields; high-field x-ray diffraction