FERMI SURFACE RIDGE AT SECOND AND THIRD UMKLAPP POSITRON ANNIHILATIONS IN YBa2Cu3074
نویسندگان
چکیده
Results of statistical noise smoothing of the electron momentum distribution got by two-dimensional angular correlation of the electron-positron annihilation radiation technique on untwinned YBa2CuaO7_ ~ single crystals are reported. Two distinct signatures of the sheet of Fermi surface related to the CuO chains (the ridge) are resolved. The first occurs at second Umklapp processes, in agreement with previous evidence. The second one, identified for the first time, occurs at third Umklapp processes. Comparison with FLAPW calculations confirms this result.
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