75As-nuclear magnetic relaxation rate (1/T1) was measured under pressure in LaFeAsO1-xFx (x = 0.08 and 0.14). For the x = 0.14 doped samples, 1/T1T = constant is observed at ambient pressure just above Tc, and application of pressure enhances the value, similar to the behavior of Tc. 1/T1T = constant originates from the Korringa relation, and an increase in DOS due to pressure application leads to the enhancement of Tc. In the case of x = 0.08, 1/T1T = constant is observed in a wide T range above T c, and the value is enhanced compared to the case of x = 0.14. The enhancement is attributable to antiferromagnetic spin fluctuation rather than an increase in DOS.
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