Spin susceptibility of neutron-irradiation-disordered YBa2Cu3O6.9 in the normal and superconducting states |
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Authors: | A V Anan’ev Yu I Zhdanov A P Gerashchenko K N Mikhalev S V Verkhovskii E Yu Medvedev K A Okulova N I Chebotaev V N Goshchitskii |
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Institution: | (1) Institute of Metal Physics, Urals Branch of the Russian Academy of Sciences, 620219 Ekaterinburg, Russia |
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Abstract: | The spin-spin relaxation rate 63
T
2
−1
of 63Cu nuclei in CuO2 layers is measured in the normal and superconducting states of the compound YBa2Cu3O6.9 (T
c
onset
=94 K) subjected to radiation-induced disordering by a fast-neutron flux Φ to T
c
onset
=68 K (Φ=7×1018 cm−2) and T
c
onset
<4 K (Φ=12×1018 cm−2). It is found that as the structural disorder increases, the contribution of the indirect spin-spin interaction 63
T
2G
−1
, which is related to the value of the spin susceptibility at the boundary of the Brillouin zone of the copper planes χs(q={π/a; π/a}), decreases slightly at the transition to the superconducting state for the initial sample and remains unchanged for the
weakly disordered sample. This behavior of the short-wavelength contribution to the spin susceptibility attests to the stability
of the x
2−y
2 symmetry of the energy gap against structural disorder, in accordance with proposed theoretical models of Cooper pairing
for high-T
c cuprates.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 3, 172–177 (10 February 1998) |
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Keywords: | |
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