Shibauchi T, Konczykowski M, van der Beek CJ, Okazaki R, Matsuda Y, Yamaura J, Nagao Y, Hiroi Z. Vortex redistribution below the first-order transition temperature in the beta-pyrochlore superconductor KOs2O6.
PHYSICAL REVIEW LETTERS 2007;
99:257001. [PMID:
18233548 DOI:
10.1103/physrevlett.99.257001]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2007] [Indexed: 05/25/2023]
Abstract
A miniature Hall-sensor array was used to detect magnetic induction locally in the vortex states of the beta-pyrochlore superconductor KOs2O6. Below the first-order transition at T{p} approximately 8 K, which is associated with a change in the rattling motion of K ions, the lower critical field and the remanent magnetization both show a distinct decrease, suggesting that the electron-phonon coupling is weakened below the transition. At high magnetic fields, the local induction shows an unexpectedly large jump at T{p} whose sign changes with position inside the sample. Our results demonstrate a novel redistribution of vortices whose energy is reduced abruptly below the first-order transition at T{p}.
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