Narumi Watanabe

Crystal growth and cylindrical Fermi surfaces of USb2

We have grown high-quality single crystals of tetragonal USb 2 using a flux method. We have detected five branches in de Haas-van Alphen (dHvA) experiments. Frequencies of all dHvA branches follow the 1/cos θ-dependence, revealing the presence of cylindrical Fermi surfaces, where θ is a tilt angle from [001] to [100]. The cyclotron masses are in the range from 1.84 to 8.33 m 0 . The two-dimensional Fermi surfaces are due to the conduction electrons in the U-plane, including the itinerant 5 f -electrons.

Fermi Surface Properties of USi3

We succeeded in growing a single crystal of USi 3 with the cubic crystal structure and measured the transverse magnetoresistance and de Haas-van Alphen(dHvA) oscillation. Fifteen dHvA branches were observed, ranging from 7.37×10 6 to 2.33×10 8 Oe. These branches are in good agreement with theoretical ones based on 5 f -itinerant FLAPW band calculations. Cyclotron masses, which are in the range from 0.39 to 4.17 m 0 , are approximately the same as the corresponding band masses. These results indicate that the itinerant 5 f -electrons form wide bands. The magnetoresistance results confirmed the existence of open orbits, which can be well explained by the band 10-electron Fermi surface.

Fermi Surface Properties of the Enhanced Pauli Paramagnet UAl3.

We succeeded in growing a high-quality single crystal of UAl 3 with the cubic AuCu 3 -type structure and studied the Fermi surface properties by measuring the de Haas–van Alphen (dHvA) effect and t...

Shubnikov-de Haas effect study of cylindrical Fermi surfaces in UAs2

Shubnikov-de Haas effect measurements were performed on a high-quality whisker single crystal of UAs2 . Complementary electrical resistivity and specific heat experiments were also carried out. Five of the seven detected branches exhibit angular dependences clearly indicating cylindrical Fermi surfaces. The effective cyclotron masses were determined to range from 0.33 to 4.5 m 0 , which yielded an electronic specific heat coefficient of 10 mJ K-2 mol-1 . This is in very good agreement with the value 11.7 mJ K-2 mol-1 determined directly by the low-temperature specific heat measurement. The two-dimensional Fermi surfaces are formed in a strongly flattened magnetic Brillouin zone and the conduction electrons are confined mainly in the U planes, indicating an important contribution of itinerant 5f electrons.

Magnetoresistance and de Haas-van Alphen effect in U3As4 and U3P4

We measured the transverse magnetoresistance and de Haas-van Alphen (dHvA) oscillation in the ferromagnetic compounds U 3 As 4 and U 3 P 4 . The magnetoresistance in both compounds increases as a f...We measured the transverse magnetoresistance and de Haas-van Alphen (dHvA) oscillation in the ferromagnetic compounds U 3 As 4 and U 3 P 4 . The magnetoresistance in both compounds increases as a function of H n (n ≃ 2) in a wide angular region, indicating that U 3 As 4 and U 3 P 4 are compensated metals. As for U 3 P 4 , the angular dependence of the magnetoresistance shows clearly dips for particular field directions. This implies the existence of a multiply-connected Fermi surface which favors open orbits along the (110) and (112) directions. We also detected several dHvA branches in U 3 As 4 and U 3 P 4 . Most of them are due to the closed Fermi surfaces, which are explained by recent results of fully relativistic spin-polarized LMTO band calculations. The cyclotron effective mass is large, ranging from 5 to 70 m 0 , and consistent with the electronic specific heat coefficient of 83 mJ/K 2 .mol in U 3 As 4 and 90 mJ/K 2 .mol in U 3 P 4 .

Cylindrical Fermi surfaces of UAs2 and UP2

Abstract We grew single crystals of tetragonal UAs2 and UP2 using chemical transport method. The residual resistivity ratio of 580 and 2900, respectively, indicated high quality of samples. Shubnikov–de Haas effect measurements performed on whisker single crystals of both compounds revealed seven fundamental oscillations in UAs2 and two in UP2. Five oscillations in UAs2 correspond to the cylindrical Fermi surfaces. The cyclotron masses in UAs2 were determined to range from 0.33m0 to 4.5m0. The two-dimensional Fermi surfaces are due to the strongly flattened magnetic Brillouin zone, the sequence of conducting U planes separated by weakly conducting As planes and, possibly, the anisotropic hybridization of 5f electrons.

Magnetoresistance and de Haas-van Alphen Effect in U3As4and U3P4

We measured the transverse magnetoresistance and de Haas-van Alphen (dHvA) oscillation in the ferromagnetic compounds U 3 As 4 and U 3 P 4 . The magnetoresistance in both compounds increases as a f...We measured the transverse magnetoresistance and de Haas-van Alphen (dHvA) oscillation in the ferromagnetic compounds U 3 As 4 and U 3 P 4 . The magnetoresistance in both compounds increases as a function of H n (n ≃ 2) in a wide angular region, indicating that U 3 As 4 and U 3 P 4 are compensated metals. As for U 3 P 4 , the angular dependence of the magnetoresistance shows clearly dips for particular field directions. This implies the existence of a multiply-connected Fermi surface which favors open orbits along the (110) and (112) directions. We also detected several dHvA branches in U 3 As 4 and U 3 P 4 . Most of them are due to the closed Fermi surfaces, which are explained by recent results of fully relativistic spin-polarized LMTO band calculations. The cyclotron effective mass is large, ranging from 5 to 70 m 0 , and consistent with the electronic specific heat coefficient of 83 mJ/K 2 .mol in U 3 As 4 and 90 mJ/K 2 .mol in U 3 P 4 .