High-Field Fermi Surface Properties in the Low-Carrier Heavy-Fermion Compound URu2Si2

概要

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We performed the Shubnikov--de Haas (SdH) experiments of the low-carrier heavy-fermion compound URu2Si2 at high fields up to 34 T and at low temperatures down to 30 mK. All main SdH branches named \alpha, \beta, and \gamma were observed for all the measured field-directions (H\parallel [001]\to [100], [100]\to [110] and [001]\to [110]), indicating that they are attributed to the closed Fermi surfaces with nearly spherical shapes. An anomalous split of branch \alpha was detected for the field along the basal plane; the split immediately disappeared by tilting the field to [001] direction, implying a fingerprint of the hidden order state. High-field experiments reveal the complicated field-dependence of the SdH frequencies and the cyclotron masses due to the Zeeman spin-splitting associated with the Fermi surface reconstruction in the hidden order state with small carrier numbers. A new SdH branch named \omega with a large cyclotron mass of 25 m_{0} was detected at high fields above 23 T close to hidden order instabilities.
2012-07-15