Publications (3)7.73 Total impact
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ABSTRACT: The Seebeck and Nernst coefficients S and nu of the highTc superconductor YBa2Cu3Oy (YBCO) were measured in a single crystal with a hole concentration p = 0.12 in magnetic fields up to H = 28 T. For temperatures down to 9 K, nu becomes independent of field by H ˜30 T, showing that by then the Nernst signal due to superconducting fluctuations has become negligible. In this fieldinduced normal state, S/T and nu/T are both large and negative in the T >0 limit. The magnitude of S/T is consistent with the small Fermi surface pocket previously detected via quantum oscillations in YBCO at a similar doping and its negative sign confirms that the pocket is electronlike. The normalstate S(T) of YBCO is remarkably similar to that of La2xBaxCuO4, La2xyNdySrxCuO4 and La2xyEuySrxCuO4 at p ˜1/8, all four materials showing a change of sign at T ˜50 K. Given that in the latter three materials this change of sign is clearly due to the onset of spin/charge density wave (`stripe') order, we infer that a similar densitywave mechanism must cause the Fermi surface reconstruction in YBCO.03/2010;  [Show abstract] [Hide abstract]
ABSTRACT: The Seebeck and Nernst coefficients S and ν of the cuprate superconductor YBa2Cu3Oy (YBCO) were measured in a single crystal with doping p = 0.12 in magnetic fields up to H = 28 T. Down to T = 9 K, ν becomes independent of field by H 30 T, showing that superconducting fluctuations have become negligible. In this fieldinduced normal state, S/T and ν/T are both large and negative in the T → 0 limit, with the magnitude and sign of S/T consistent with the small electronlike Fermi surface pocket detected previously by quantum oscillations and the Hall effect. The change of sign in S(T) at T 50 K is remarkably similar to that observed in La2−xBaxCuO4, La2−x−yNdySrxCuO4 and La2−x−yEuySrxCuO4, where it is clearly associated with the onset of stripe order. We propose that a similar densitywave mechanism causes the Fermi surface reconstruction in YBCO.Physical Review Letters, v.104, 05700510570054 (2010). 03/2010;  [Show abstract] [Hide abstract]
ABSTRACT: The Seebeck and Nernst coefficients S and nu of the cuprate superconductor YBa{2}Cu{3}O{y} (YBCO) were measured in a single crystal with doping p=0.12 in magnetic fields up to H=28 T. Down to T=9 K, nu becomes independent of field by H approximately 30 T, showing that superconducting fluctuations have become negligible. In this fieldinduced normal state, S/T and nu/T are both large and negative in the T>0 limit, with the magnitude and sign of S/T consistent with the small electronlike Fermi surface pocket detected previously by quantum oscillations and the Hall effect. The change of sign in S(T) at T approximately 50 K is remarkably similar to that observed in La2xBaxCuO4, La{2xy}Nd{y}Sr_{x}CuO{4}, and La{2xy}Eu{y}Sr{x}CuO{4}, where it is clearly associated with the onset of stripe order. We propose that a similar densitywave mechanism causes the Fermi surface reconstruction in YBCO.Physical Review Letters 02/2010; 104(5):057005. · 7.73 Impact Factor
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20  Citations  
7.73  Total Impact Points  
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2010

Université de Sherbrooke
 Department of Physics
Sherbrooke, Quebec, Canada
