Magnetic Structure of Phase II in U ( Ru 0.96 Rh 0.04 ) 2 Si 2 Determined by Neutron Diffraction under Pulsed High Magnetic Fields

K. Kuwahara (1) , S. Yoshii (2) , H. Nojiri (2) , D. Aoki (2) , William Knafo (3) , F. Duc (3) , Xavier Fabrèges (3) , Gernot Werner Scheerer (3) , P. Frings (3) , Rikken G.L.J.A. (3) , F. Bourdarot (4, 5) , L. Regnault (5) , J. Flouquet (6)

1 Ibaraki University
2 Tohoku University [Sendai]
3 LNCMI-T - Laboratoire national des champs magnétiques intenses - Toulouse
4 SPSMS - UMR 9001 - Service de Physique Statistique, Magnétisme et Supraconductivité
5 MDN - Magnétisme et Diffusion Neutronique
6 LCP - Laboratoire de Cryophysique

We report neutron diffraction measurements on U(Ru0.96Rh0.04)2Si2 single crystal under pulsed high magnetic fields up to 30 T applied along the tetragonal c axis. The high-field experiments revealed that the field-induced phase II above 26 T corresponds to a commensurate up-up-down ferrimagnetic structure characterized by the wave vector q=(2/3,0,0) with the magnetic moments parallel to the c axis, which naturally explains the one-third magnetization plateau and the substantially changed Fermi surface in phase II. This a-axis modulated magnetic structure indicates that the phase II near the hidden order phase is closely related to the characteristic incommensurate magnetic fluctuations at Q1=(0.6,0,0) in the pure system URu2Si2, in contrast to the pressure-induced antiferromagnetic order at Q0=(1,0,0).

Domaines: Physique [physics]; Science des matériaux [cond-mat.mtrl-sci]; Supraconductivité [cond-mat.supr-con]

K. Kuwahara, S. Yoshii, H. Nojiri, D. Aoki, William Knafo, et al.. Magnetic Structure of Phase II in U ( Ru 0.96 Rh 0.04 ) 2 Si 2 Determined by Neutron Diffraction under Pulsed High Magnetic Fields. Physical Review Letters, 2013, 110 (21), pp.216406. ⟨10.1103/PhysRevLett.110.216406⟩. ⟨hal-02146918⟩