S. Sakatsume

Acoustic de Haas-Van Alphen effect in LaSb and CeSb

Abstract We have investigated the de Haas-van Alphen effect in LaSb and CeSb by means of an ultrasound velocity measurement. Anisotropic electron-strain interactions on the Fermi surfaces in LaSb were found by the field angle dependence of the oscillatory intensity of the longitudinal C11 mode. The large and heavy hole β4, which was predicted by the p-f mixing model, has been found in CeSb. The cyclotron effective mass of β4 was 4.2m0.

Heavy hole state in CeSb

Abstract We have measured the dHvA effect of CeSb down to 50 mK and discovered the largest hole Fermi surface, β 4 . The relative large electronic specific heat coefficient of CeSb compared with that of LaSb has been observed. These results are interpreted by the band calculation based on the p-f mixing model.

Low-temperature properties of the dense Kondo system Ce0.5La0.5B6

Low-temperature specific heat and electric resistivity of the dense Kondo compound Ce 0.5 La 0.5 B 6 have been measured. The specific heat for H =0 shows a broad peak at around 0.9 K corresponding to the Kondo effect. No indication of magnetic or quadrupolar phase transition is observed down to 100 mK for H =0. Very large specific heat coefficients of γ=1.8 J/K 2 mol and β=2.9 J/K 4 mol for H =0 indicate the Kondo singlet ground state without long-range ordering.

Metamagnetic transition in NdB6 with a small magnetic anisotropy in low magnetic fields

The high-field magnetization measurement of the antiferro (AF) magnetic compound NdB 6 , which has a small magnetic anisotropy in low magnetic fields, revealed an unexpected metamagnetic transition. This is observed only for H ∥ , while the magnetization curve for H ∥ and is normal, as usually observed in an AF magnet with a small magnetic anisotropy. To our knowledge, this is the first example of the anisotropic magnetic field induced metamagnetic transition for a compound with a small magnetic anisotropy in low magnetic fields.

A New Mass-Enhanced Ferromagnet: U2PtSi3

We have newly found and succeeded in growing a mass-enhanced ferromagnet U 2 PtSi 3 . The electronic specific heat coefficient is 200 mJ/K 2 per mole of U. The magnetization shows no saturation up to 80 kOe for both the a - and c -axes. The magnitude of remanence is much smaller compared with the effective moment in the paramagnetic phase. Experimental results on single-crystalline samples are presented and discussed.

Magneto-acoustic effect of CeCu6 at low temperatures

Low temperature properties of the elastic constants C 11 and C 33 in the heavy electron compound CeCu 6 have been investigated. The remarkable amount of softening below the Kondo temperature down to 20 mK reflects the heavy electron state at the Fermi surface. The oscillations of the C 33 mode under a magnetic field along the c axis have been found at low temperature ranges below 500 mK.

Acoustic de Haas-van Alphen Effect of CeB6 and LaB6

All of the main orbits of LaB6 have been observed successfully by the ultrasonic measurement of dHvA oscillations of elastic constants without field modulation technique, where the high resolution important. Adopting the ultrasonic technique in a dilution refrigerator, the acoustic dHvA oscillation of CeB6 is obtained for the heavy fermion with effective cyclotron mass ~7.2m0 of the extremal orbit 0.012 A-2(1.26MG)

Elastic Properties of Dense Kondo Compounds CeNiSn and CePdSn

Elastic properties of the dense Kondo compounds CeNiSn and CePdSn with orthorhombic structure have been investigated by the ultrasonic measurements. The anomalous softening of the longitudinal C 11 , C 22 and C 33 modes in CeNiSn is responsible for the energy gap at the Fermi level in the quasiparticle band. A remarkable anisotropic behavior on the resistivity as well as the elastic constant in the magnetic field along the crystallographic a , b , c -axes has been observed. In CePdSn, the softening in the longitudinal C 22 and C 33 modes has been found.

Acoustic de Haas-van Alphen effect in f-electron systems*

The acoustic de Haas-van Alphen effects of CeCu 2 , YCu 2 and UB 12 have been observed by the sound velocity measurements. The angular variation of the frequencies and the mass enhancement effect are determined.

Anisotropy of Zeeman Effects in Optical Absorption Spectra of Tetragonal Crystals Cs3CoCl5 and Cs3CoBr5. I. Experimental Results

Dependences of Zeeman patterns on the direction and the strength of magnetic fields H 0 applied perpendicularly to the c -axis, are investigated in 16500 cm -1 ∼27000 cm -1 at 20 K∼1.3 K by using H 0 up to 78 kOe in the following three arrangements; E ⊥ c and E // H 0 , E ⊥ c and E ⊥ H 0 and E // c , where E is the electric vector of the incident light. Optical anisotropies depend on the mutual directions between E and H 0 , and in some cases depend on the direction of H 0 itself with periodicity π/2. While, Zeeman splittings are independent of the direction of H 0 in all cases. It is determined by analyzing anisotropies of Zeeman spectra, whether the excited state is \(\varGamma_{6}\) or \(\varGamma_{7}\), and whether its g ⊥ -value is positive or negative. The ratio between the two transition moments of transitions from | 4 A 2 ±1/2> and | 4 A 2 ±3/2> to a certain excited Kramers doublet is determined from dependences of the intensity on the strength of H 0 in several cases.