In-Plane Anisotropy of Transport Property in BaTbO3-Doped SmBa2Cu3Oy Films

BaTbO
₃
(BTbO) is one of the artificial pinning center materials and forms thick rectangular nanorods with diameters of ∼20 nm when it is doped high. We expected that the rectangular nanorods would produce in-plane anisotropy of flux pinning. In this paper, we investigated in-plane anisotropy of transport properties in BTbO-doped SmBa
₂
Cu
₃
O
_y
(SmBCO) films. SmBCO thin films with various contents of BtbO were fabricated by using a pulsed laser deposition method. To investigate the in-plane anisotropy, the critical current density
J
_c
was measured at 77 K, 0–9 T, and
φ
= 0° and 45°, where
φ
was defined as an in-plane angle from the
a
or
b
-axes of SmBCO. To fix the direction of current in the films, the microbridges were fabricated with different
φ
(=0° and 45°) by using the laser etching technique. As a result,
J
_c
at
φ
= 0° was higher than the one at
φ
= 45° in the films with BTbO contents of 12.0 and 20.0 vol.% at 77 K and at fields of 5 T or more. The anisotropy of
J
_c
in high fields for current directions was possibly explained by the rectangular shape of the BTbO nanorods.