Anomalous physical properties of underdoped weak-ferromagnetic superconductor RuSr2EuCu2O8

作者：Chang B C; Ku H C^*; Ho J C

来源：Physica B: Condensed Matter , 2008, 403(5-9): 1147-1148.

DOI：10.1016/j.physb.2007.10.350

• weak-ferromagnetic superconductor
• spontaneous vortex state

Similar to the optimal-doped, weak-ferromagnetic (WFM induced by canted antiferromagnetism, T-Curie = 131 K) and superconducting (T-c = 56 K) RuSr2GdCu2O8, the underdoped RuSr2EuCu2O8 (T-Curie = 133 K, Tc = 36 K) also exhibits a spontaneous vortex state (SVS) between 16 and 36 K. The low field superconducting hysteresis loop indicates a weak and narrow Meissner state region of average lower critical field B-cl(ave)(0) = 7 G and T-SVS = 16 K. The vortex melting transition (T-melting = 21 K) below T-c obtained from the broad resistivity drop and the onset of diamagnetic signal indicates a vortex liquid region due to the coexistence and interplay between superconductivity and WFM order. No visible jump in specific heat was observed near T-c. This is not surprising, since the electronic specific heat is easily overshadowed by the large phonon and weak-ferromagnetic contributions. Furthermore, a broad resistivity transition due to low vortex melting temperature would also lead to a correspondingly reduced height of any specific heat jump.

• 出版日期2008-4-1
• 单位清华大学