Pump–probe Spectroscopy with Uniaxial Strain for BaV10O15

We performed a pump–probe optical reflectivity measurement with an applied uniaxial strain for bulk single crystals of BaV10O15 at room temperature. We found that with a compressive strain of ΔL/L = −3.0 × 10−3 along the b-axis, the oscillation in the time dependence of the photoinduced reflectivity change, which arises from the propagation of shockwave, becomes longer in period, indicating that the sound velocity decreases on the order of 10−2. This result implies that the elastic modulus of BaV10O15 is coupled with the correlation of the orbital degree of freedom of V t2g electrons.