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arXiv · cond-mat/0609487

Magnetic field induced lattice anomaly inside the superconducting state of CeCoIn$_5$: evidence of the proposed Fulde-Ferrell-Larkin-Ovchinnikov state

Abstract

We report high magnetic field linear magnetostriction experiments on CeCoIn$_5$ single crystals. Two features are remarkable: (i) a sharp discontinuity in all the crystallographic axes associated with the upper superconducting critical field $B_{c2}$ that becomes less pronounced as the temperature increases; (ii) a distinctive second order-like feature observed only along the c-axis in the high field (10 T $ \lesssim B \leq B_{c2}$) low temperature ($T \lesssim$ 0.35 K) region. This second order transition is observed only when the magnetic field lies within 20$^o$ of the ab-planes and there is no signature of it above $B_{c2}$, which raises questions regarding its interpretation as a field induced magnetically ordered phase. Good agreement with previous results suggests that this anomaly is related to the transition to the Fulde-Ferrel-Larkin-Ovchinnikov superconducting state.

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V. F. Correa, T. P. Murphy, C. Martin, K. M. Purcell, E. C. Palm, G. M. Schmiedeshoff, J. C. Cooley, S. W. Tozer. 2006-09-19. Magnetic field induced lattice anomaly inside the superconducting state of CeCoIn$_5$: evidence of the proposed Fulde-Ferrell-Larkin-Ovchinnikov state. https://doi.org/10.1103/physrevlett.98.087001

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