Epitaxial thin films of lanthanum-deficient LaxMnO3−δ (0.67≤x≤1) have been grown on (100) SrTiO3 substrates by pulsed laser deposition. The as-deposited films exhibit a ferromagnetic transition at temperatures ranging from 115 to 240 K, with the transition temperature (Tc) increasing with higher La deficiency. A sharp drop in resistivity and negative magnetoresistance is observed close to Tc, a behavior similar to that observed in divalent substituted La1−xMxMnO3−δ (M=Ba, Sr, Ca, Pb) films. Postannealing the films in O2 reduces the resistivity and raises the Tc to values close to room temperature. A magnetoresistance value of 130% (Δρ/ρH) has been obtained at 300 K at 4 T for a post-annealed film with x=0.75.
A high-resolution scanning superconducting quantum interference device microscopy study of tetragonal single-layer Tl
2
Ba
2
CuO
6+δ
films, deposited on tricrystal SrTiO
3
substrates, demonstrates the effect of spontaneously generated half flux quanta. This observation shows that in addition to YBa
2
Cu
3
O
7
, the order parameter symmetry in Tl
2
Ba
2
CuO
6+δ
is consistent with that of a
d
x
2
-
y
2
pair state. This result also rules out any bilayer or twinning effects and any pairing that is incompatible with the fourfold rotational symmetry as in the Tl
2
Ba
2
CuO
6+δ
superconducting system.
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