TY - JOUR

T1 - Effect of rotation on the elastic moduli of solid He 4

AU - Tsuiki, T.

AU - Takahashi, D.

AU - Murakawa, Satoshi

AU - Okuda, Y.

AU - Kono, K.

AU - Shirahama, K.

PY - 2018/2/23

Y1 - 2018/2/23

N2 - We report measurements of elastic moduli of hcp solid He4 down to 15 mK when the samples are rotated unidirectionally. Recent investigations have revealed that the elastic behavior of solid He4 is dominated by gliding of dislocations and pinning of them by He3 impurities, which move in the solidlike Bloch waves (impuritons). Motivated by the recent controversy of torsional oscillator studies, we have performed direct measurements of shear and Young's moduli of annular solid He4 using pairs of quarter-circle-shape piezoelectric transducers (PZTs) while the whole apparatus is rotated with angular velocity Ω up to 4 rad/s. We have found that shear modulus μ is suppressed by rotation below 80 mK, when shear strain applied by PZT exceeds a critical value, above which μ decreases because the shear strain unbinds dislocations from He3 impurities. The rotation-induced decrement of μ at Ω=4 rad/s is about 14.7(12.3)% of the total change of temperature dependent μ for solid samples of pressure 3.6(5.4) MPa. The decrements indicate that the probability of pinning of He3 on dislocation segment G decreases by several orders of magnitude. We propose that the motion of He3 impuritons under rotation becomes strongly anisotropic by the Coriolis force, resulting a decrease in G for dislocation lines aligning parallel to the rotation axis.

AB - We report measurements of elastic moduli of hcp solid He4 down to 15 mK when the samples are rotated unidirectionally. Recent investigations have revealed that the elastic behavior of solid He4 is dominated by gliding of dislocations and pinning of them by He3 impurities, which move in the solidlike Bloch waves (impuritons). Motivated by the recent controversy of torsional oscillator studies, we have performed direct measurements of shear and Young's moduli of annular solid He4 using pairs of quarter-circle-shape piezoelectric transducers (PZTs) while the whole apparatus is rotated with angular velocity Ω up to 4 rad/s. We have found that shear modulus μ is suppressed by rotation below 80 mK, when shear strain applied by PZT exceeds a critical value, above which μ decreases because the shear strain unbinds dislocations from He3 impurities. The rotation-induced decrement of μ at Ω=4 rad/s is about 14.7(12.3)% of the total change of temperature dependent μ for solid samples of pressure 3.6(5.4) MPa. The decrements indicate that the probability of pinning of He3 on dislocation segment G decreases by several orders of magnitude. We propose that the motion of He3 impuritons under rotation becomes strongly anisotropic by the Coriolis force, resulting a decrease in G for dislocation lines aligning parallel to the rotation axis.

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U2 - 10.1103/PhysRevB.97.054516

DO - 10.1103/PhysRevB.97.054516

M3 - Article

AN - SCOPUS:85043783285

VL - 97

JO - Physical Review B-Condensed Matter

JF - Physical Review B-Condensed Matter

SN - 2469-9950

IS - 5

M1 - 054516

ER -