The Electronic Structure of La ₂ BaCuO ₅ : A Magnetic Insulator

Abstract

The results of density functional calculations of the electronic structure of La2BaCu06 are presented. The calculations used the standard spin-polarized Local Density Approximation. The system is found to be a strong ferromagnet and has an insulating ground state. The results of the calculations show excellent agreement with the electronic configurations, magnetic ordering, and the localized magnetic moments inferred from experiments.

JosephsonπState in a Ferromagnetic Insulator

“…6 in Ref. 12). The mirror image of the minority spin band with respect to the Fermi energy corresponds to the hole band with minority spin in the Bogoliubov-de Gennes picture.…”

“…Here we focus on La 2 BaCuO 5 (LBCO) [11] which is an important representative FI in spintronics. According to a first-principle band calculation [12], the bottom of the minority spin band is at the Γ point whose wave number is (k a , k b , k c ) = (0, 0, 0), where k j for j = a, b, and c is the wave number along j axis (see Fig. 6 in Ref.…”

“…Note that it is impossible to realize the π-state if current flows in the ab-plane. This is because wave numbers in ab-plane at the bottom of the minority spin band and those at the top of the majority spin band are given by the same wave number (k a , k b ) = (0, 0) [12].…”

Theory of quantum transport in Josephson junctions with a ferromagnetic insulator

“…In 1990, Mizuno et al, found that LBCO undergoes a ferromagnetic transition at 5.2 K [24]. The exchange splitting ex V is estimated to be 0.34 eV by a first-principle band calculation using the spin-polarized local density approximation [27]. Since the exchange splitting is large and the bands are originally half-filled, the system becomes FI.…”

“…The tight binding parameters t and g have been determined by fitting to the first-principle band structure calculations [27]. The formation of the π-junction can be experimentally detected by using a HTSC ring [see Fig.…”