INVESTIGADORES
FABRICIUS Gabriel
artículos
Título:
Pressure dependence of the electric-field gradients in YBa2Cu4O8
Autor/es:
C.O. RODRIGUEZ; G. FABRICIUS; M.G. STACHIOTTI; N.E. CHRISTENSEN
Revista:
PHYSICA C - SUPERCONDUTIVITY
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Lugar: Amsterdam; Año: 1997 vol. 282 p. 1619 - 1620
ISSN:
0921-4534
Resumen:
The behaviour of the electric field gradients (EFGs) at all nuclear sites for YBa2Cu4O8
(Y124) under pressure have been obtained within the Local Density
Approximation (LDA) to density functional (DFT), using the FP-LAPW
method. The need for using an extended basis to deal with errors due to
extended core states or linearization of narrow states is demonstrated
by comparing our results to those obtained using the more standard two
panel scheme. The calculated EFGs at ambient pressure for plane and
chain Cu and O sites agree with already published theoretical values,
but those of Y and Ba are quite different. The EFG's for which there
exist experimental determinations are reproduced except for plane-Cu,
where a factor 3 discrepancy is found. This is similar to the case of
Y123, where the EFG's of the plane-Cu were off by a factor of 2. The
smaller predicted anisotropy has been attributed to a real failure of
LDA. As pressure is increased the calculated EFGs at plane-sites remain
practically constant. Since many properties of Y124, including Tc,
are very sensitive to pressure we propose that experimental evaluation
of the EFGs under pressure could be used to give insight to charge
redistributions in the CuO2 planes and to examine further the validity of predictions based of LDA calculations for High Tc materials(HTSC)