Title :
Anisotropic magnetic and transport properties of UNiGe
Author :
Prokes, K. ; Nakotte, H. ; Bruck, E. ; de Boer, F.R. ; Havela, L. ; Sechovsky, V. ; Svoboda, P. ; Maletta, H.
Author_Institution :
Van der Waals Lab., Amsterdam Univ., Netherlands
fDate :
3/1/1994 12:00:00 AM
Abstract :
Magnetism in UNiGe which adopts the orthorhombic TiNiSi type of structure with lattice constants a=700.7 pm, b =423.7 pm, c=720.7 pm is strongly anisotropic. The Curie-Weiss behaviour of the susceptibility above 80 K yields values of Θp equal to -98, 3 and 41 K for the a, b and c axis, respectively. Also the electrical resistivity is anisotropic and reflects magnetic phase transitions at 41.5 and 50 K, in very good agreement with specific-heat data. An antiferromagnetic structure of U moments of about 1.4 μB with a propagation vector q=(0, 0.5, 0.5) can be concluded from neutron-diffraction studies at low temperatures. Two metamagnetic transitions are observed in high-field magnetization data at 4.2 K in fields applied along the b (at 17 and 25 T) and c (at 3 and 10 T) axes yielding parallel alignment of the magnetic moments in fields above the second transition. The magnetization measured at 35 T amounts to 1.45 μB/f.u. The huge magnetic anisotropy is reflected in the weak linear magnetic response to fields along the a axis yielding only 0.23 μB/f.u. at 35 T. The destruction of antiferromagnetic ordering in high fields is accompanied by a reduction of about 80 of the electrical resistivity. The huge magnetic anisotropy and giant magnetoresistance which is also observed in other UTX compounds (T=transition metal, X=p-metal) can be understood in terms of anisotropic 5f-ligand hybridization
Keywords :
electrical conductivity of crystalline metals and alloys; germanium alloys; magnetic anisotropy; magnetic structure; magnetic transitions; nickel alloys; paramagnetic properties of substances; uranium alloys; 4.2 K; 80 K; Curie-Weiss behaviour; UNiGe; anisotropic 5f-ligand hybridization; antiferromagnetic structure; electrical resistivity; high-field magnetization data; huge magnetic anisotropy; lattice constants; magnetic phase transitions; metamagnetic transitions; neutron-diffraction; strongly anisotropic; susceptibility; transport properties; weak linear magnetic response; Anisotropic magnetoresistance; Antiferromagnetic materials; Electric resistance; Lattices; Magnetic anisotropy; Magnetic moments; Magnetic properties; Magnetization; Perpendicular magnetic anisotropy; Temperature;
Journal_Title :
Magnetics, IEEE Transactions on