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Journal Articles

NQR measurements of UTGa $_{5}$

Kato, Harukazu; Sakai, Hironori; Kambe, Shinsaku; Walstedt, R. E.; Tokiwa, Yoshifumi; Onuki, Yoshichika

Acta Physica Polonica B, 34(2), p.1063 - 1066, 2003/09

http://www.actaphys.uj.edu.pl/_cur/store/vol34/pdf/v34p1063.pdf

We performed $^{69,71}$ Ga-NMR/NQR studies for UPtGa $_{5}$ , which is a 5-itinerant antiferromagnets with Neel temperature $T_{N}$ = 26 K and an electronic specific coefficient = 57 mJ/mol K $^{2}$ . From the NMR spectrum in the paramagnetic temperature region, the hyperfine coupling constants $A_{hf}^{para}$ in the paramagnetic state have been evaluated. The magnitude of the transferred field has been evaluated from the zero-applied-field spectrum, yielding a value for the hyperfine coupling constant $A_{hf}^{AF}$ in the antiferromagnetic state. The estimated value of $A_{hf}^{AF}$ is an order of magnitude larger than that of $A_{hf}^{para}$ . This implies the existence of a long-ranged hyperfine interaction path. The mechanism of the hyperfine interaction will be discussed in terms of RKKY interactions.

Journal Articles

Magnetic excitations in an itinerant 5 antiferromagnet UPt $_{2}$ Si $_{2}$

Metoki, Naoto; Koike, Yoshihiro; Haga, Yoshinori; Bernhoeft, N.*; Lander, G. H.*; Tokiwa, Yoshifumi; Onuki, Yoshichika

Acta Physica Polonica B, 34(2, Part2), p.979 - 982, 2003/02

http://www.actaphys.uj.edu.pl/_cur/store/vol34/pdf/v34p0979.pdf

no abstracts in English

Journal Articles

Pressure effect on antiferromagnetic ordering in UPb

Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika; Nakashima, Miho*; Aoki, Dai*; Onuki, Yoshichika*; Hedo, Masato*; Uwatoko, Yoshiya*

Acta Physica Polonica B, 34(2), p.1239 - 1242, 2003/02

http://www.actaphys.uj.edu.pl/_cur/store/vol34/pdf/v34p1239.pdf

Uranium intermetallic compounds UX (X = Si, Ge, Sn, Pb) form a ariety of magnetic properties including Pauli paramagnetism in USi and UGe, spin fluctuations in USn and antiferromagnetism in UPb. Among them, UPb is an antiferromagnet below the Nel temperature 32 K with a large electronic specific heat = 110 mJ/Kmol. In this study we present the electrical resistivity measurement under high pressure up to 8 GPa. We found that at low pressure $T_{rm N}$ increases with increasing pressure. It has a maximum value 36 K at 3 GPa, then decreases with increasing pressure.In addition we observed an additional resistive anomaly followed by a steep decrease in resistivity below $T_{rm N}$ under pressure.The maximum pressure 8 GPa in the present study was not enough to suppress the antiferromagnetic transition.The critical pressure is estimated to be around 12 GPa.

Journal Articles

Single crystal growth and magnetic properties of ferromagnetic URhGe

Matsuda, Tatsuma; Haga, Yoshinori; Tokiwa, Yoshifumi; Andrei, G.; Yamamoto, Etsuji; Okubo, Tomoyuki*; Onuki, Yoshichika

Acta Physica Polonica B, 34(2), p.1071 - 1074, 2003/02

http://www.actaphys.uj.edu.pl/_cur/store/vol34/pdf/v34p1071.pdf

We have successfully grown a single crystal of uranium intermetallic compound URhGe. The temperature dependence of electrical resistivity shows highly anisotropic behavior. Two anomalies, which correspond to the magnetic ordering temperatures, were observed in the resistivity, magnetic susceptibility and specific heat measurements at $T_{rm M1}$ = 30 K and $T_{rm M2}$ =25 K. The magnetic susceptibility also shows a large uniaxial anisotropy with a magnetic easy-axis along the [010] direction.