Abstract for an Invited Paper for the MAR11 Meeting of The American Physical Society Superclimb of Dislocations in Solid 4He1

for an Invited Paper for the MAR11 Meeting of The American Physical Society Superclimb of Dislocations in Solid 4He1 ANATOLY KUKLOV, CSI, CUNY Edge dislocation with superfluid core can perform superclimb – non-conservative motion (climb) assisted by superflow along its core. Such dislocation, with Burgers vector along the C-axis, has been found in ab initio simulations of hcp solid 4He [1]. Uniform network of superclimbing dislocations can induce isochoric compressibility χ = dN/dμ which is finite (in contrast to ideal solid where it vanishes) and, practically, independent of the network density. Here N is total number of atoms and μ is chemical potential [1]. Such giant response has been observed by Ray and Hallock during superfluid flow events through solid He4 [2]. Study [3] of superclimbing dislocation within the model of Granato-Lücke string, subjected to Peierls potential and to vanishing bias by μ, has found that χ exhibits wide peak in the intermediate range of temperatures (T) above some Tp determined by Peierls energy and below Ts ∼ 0.5K above which superfluidity of the core essentially vanishes. Non-Luttinger type behavior characterized by χ ∼ Lb scaling as some power 1 < b ≤ 2 of dislocation length L is observed in the wide peak region. Biasing superclimbing dislocation by finite μ (due to a contact with liquid 4He through vycor electrodes [2],[4]) can induce core roughening caused by thermally assisted tunneling of jog-antijog pairs through the barrier produced by combination of Peierls potential and the bias [5]. The threshold for this effect scales as μc ∼ 1/La with some power a ≈ 1.7. The roughening is found to be hysteretic below some temperature Thyst. At Thyst < T < TR, with TR determining temperature of thermal roughening, χ exhibits strong and narrow resonant peak leading to a dip in the core superfluid sound velocity. This mechanism is proposed as an explanation for a strong and narrow dip observed in critical superflow rate [4]. It is found that the dip characteristics are sensitive to the bias by μ and, therefore, this can be used as a test for the proposed mechanism. It is also predicted that the dip depth at given T should be periodic in μ with the period ∼ μc. [1] S. G. Söyler, et. al., PRL bf 103, 175301 (2009). [2] M. W. Ray and R. B. Hallock, PRL 100, 235301 (2008) ; PRB 79, 224302 (2009); PRB 81, 214523 (2010); Phys. Rev. B82, 012502 (2010); [3] D. Aleinikava, et al., JLTP, to be published; [4] M. W. Ray and R. B. Hallock , Phys. Rev. Lett. 105, 145301 (2010); [5] D. Aleinikava and A.B. Kuklov, unpublished. 1This work was supported by NSF, grants PHY1005527 and PHY0653135,and by CUNY, grant 63071-00 41