Torsional Oscillator Measurements of Liquid 4He Confined in 2.5-nm Channel of FSM

We have performed torsional oscillator measurements for liquid 4He confined in 2.2-nm channels of FSM up to 2.45 MPa. At 0.1 MPa, the resonant frequency increases with decreasing temperature. It shows a small bend at about 0.9 K, and then keeps increasing down to the lowest temperature, 0.16 K. The magnitude of the frequency increase below 0.9 K is suppressed with increasing pressure, while the temperature of the bend shows almost no pressure dependence.