Large copper isotope effect on the pseudogap in the high-temperature superconductor HoBa2Cu4O8статья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:The copper isotope effect ((CU)-C-63 vs. (CU)-C-65) On the relaxation rate of crystal-field excitations in the slightly underdoped high-temperature superconductor HoBa2Cu4O8 has been investigated by inelastic neutron scattering. For the 63CU compound there is clear evidence for the opening of an electronic gap in the normal state at T* approximate to 160 K far above T-c = 79.0 K. Upon substitution of (CU)-C-63 by (CU)-C-65, T-c decreases marginally to 78.6 K, whereas T* is increased to about 185 K. This large copper isotope shift DeltaT*(Cu) = T*((65) Cu) - T* ((63) CU) 77 approximate to 25 K - together with the corresponding oxygen isotope shift DeltaT*(O) = T*(O-18) - T*(O-16) approximate to 50 K found in an earlier investigation - suggests that phonons or lattice fluctuations involving both the copper and the oxygen ions are important for the pairing mechanism in high-T-c materials.