A sign of anticorrelation between the orbital related order and the superconductivity in LiTi₂O_4-δ system

Previously studies show that for the Li_1+xTi_2-xO_4-δ(x<1/3) samples grown below a certain oxygen pressure, T_c0 remains the same whereas the orbital related order become weaker as the oxygen pressure increasing. It seems that the superconductivity of those samples isn’t obviously related to the orbital related order. However, it is recently founded that, for those samples, there is a small linear region exists in temperature dependent resistance curve (R-T curve) above the superconducting state, and the temperature that the R-T curve begin to deviate from this linear region at the low temperature side enhances with the increase of the oxygen pressure. The suppressive effect of current on superconductivity shows that this temperature is the beginning of the superconductivity. Therefore, it indicates that the superconductivity is actually strengthened as the oxygen pressure increasing, contrary to the effect of the oxygen pressure on the orbital related order. Moreover, a new superconducting film similar to LiTi₂O_4-δ has been synthesized by PLD, which shows more directly that the superconductivity can be weakened by the orbital order.