Solid 4He and the Supersolid Phase: from Theoretical Speculation to the Discovery of a New State of Matter? A Review of the Past and Present Status of Research

Abstract

The possibility of a supersolid state of matter, i.e., a crystalline solid exhibiting superfluid properties, first appeared in theoretical studies about forty years ago. After a long period of little interest due to the lack of experimental evidence, it has attracted strong experimental and theoretical attention in the last few years since Kim and Chan (Penn State, USA) reported evidence for nonclassical rotational inertia effects, a typical signature of superfluidity, in samples of solid 4He. Since this "first observation", other experimental groups have observed such effects in the response to the rotation of samples of crystalline helium, and it has become clear that the response of the solid is extremely sensitive to growth conditions, annealing processes, and 3He impurities. A peak in the specific heat in the same range of temperatures has been reported as well as anomalies in the elastic behaviour of solid 4He with a strong resemblance to the phenomena revealed by torsional oscillator experiments. Very recently, the observation of unusual mass transport in hcp solid 4He has also been reported, suggesting superflow. From the theoretical point of view, powerful simulation methods have been used to study solid 4He, but the interpretation of the data is still rather difficult; dealing with the question of supersolidity means that one has to face not only the problem of the coexistence of quantum coherence phenomena and crystalline order, exploring the realm of spontaneous symmetry breaking and quantum field theory, but also the problem of the role of disorder, i.e., how defects, such as vacancies, impurities, dislocations, and grain boundaries, participate in the phase transition mechanism.

Published on J. Phys. Soc. Jpn., Vol.77, No.11, p.111010

References in corpus (48)

• Supersolid hardcore bosons on the triangular lattice
• Low Temperature Shear Modulus Changes in Solid 4-He and Connection to Supersolidity
• Persistent supersolid phase of hard-core bosons on the triangular lattice
• Monte Carlo Analysis of a New Interatomic Potential for He
• Luttinger Liquid in the Core of Screw Dislocation in Helium-4
• Superglass Phase of Helium-four
• Disorder and the Supersolid State of Solid ${}^4$He
• On the Supersolid State of Matter
• Oscillation Frequency Dependence of Non-Classical Rotation Inertia of Solid ${}^4$He
• Superfluidity of Grain Boundaries in Solid Helium-4
• Ring exchanges and the supersolid phase of 4He
• Observation of Unusual Mass Transport in Solid hcp 4He
• The fate of vacancy-induced supersolidity in 4He
• What makes a crystal supersolid ?
• Pressure-driven flow of solid helium
• Observation of non-classical rotational inertia in bulk solid 4He
• Supersolid Helium at High Pressure
• Off-Diagonal Long-Range Order in Solid 4He
• Two New Vortex Liquids
• Annealing Effect for Supersolid Fraction in ${}^4$He
• Nonclassical Rotational Inertia in Single Crystal Helium
• On the origin of the decrease in the torsional oscillator period of solid He4
• Freezing and pressure-driven flow of solid helium in Vycor
• Local stress and superfluid properties of solid Helium-4
• Thermodynamics of an incommensurate quantum crystal
• Coexisting ordinary elasticity and superfluidity in a model of defect-free supersolid
• The effect of 3He impurities on the nonclassical response to oscillation of solid 4He
• Thermal History of Solid 4He Under Oscillation
• Bose Einstein Condensation of incommensurate solid 4He
• Squeezing superfluid from a stone: Coupling superfluidity and elasticity in a supersolid
• Superfluidity of Dense ${}^4$He in Vycor
• Observation of a new excitation in bcc solid 4He by inelastic neutron scattering
• Wetting Properties of Grain Boundaries in Solid Helium 4
• Bose Einstein Condensation in solid 4He
• Quenched Dislocation Enhanced Supersolid Ordering
• The Debye-Waller Factor in solid 3He and 4He
• Bose Fluids Above Tc: Incompressible Vortex Fluids and "Supersolidity"
• Ginsburg-Landau theory of supersolid
• Absence of low temperature anomaly in the Debye-Waller factor of solid He-4
• Melting curve of ${}^4$He: no sign of the supersolid transition down to 10 mK
• Supersolidity and phase diagram of softcore bosons in a triangular lattice
• Theory for supersolid ${}^4$He
• Absence of low temperature anomaly on the melting curve of ${}^4$He
• Observation of Macroscopic Structural Fluctuations in bcc Solid 4He
• Bounds for the Superfluid Fraction from Exact Quantum Monte Carlo Local Densities
• Path Integral Calculations of exchange in solid 4He
• Two-body correlations and the superfluid fraction for nonuniform systems
• New excitations in bcc ${}^4$He - an inelastic neutron scattering study

Cited by in corpus (25)

• Three-dimensional Roton-Excitations and Supersolid formation in Rydberg-excited Bose-Einstein Condensates
• Supersolids: what and where are they ?
• New states of matter with fine-tuned interactions: quantum droplets and dipolar supersolids
• Exciton supersolidity in hybrid Bose-Fermi systems
• Hydrodynamic theory of supersolids: Variational principle and effective Lagrangian
• Simultaneous Measurement of Torsional Oscillator and NMR of Very Dilute 3He in Solid 4He
• Mass flow through solid 4He induced by the fountain effect
• Low frequency acoustics in solid ${}^4$He at low temperature
• Quantum Monte Carlo study of a vortex in superfluid ${}^4$He and search for a vortex state in the solid
• Properties of Vacancy Formation in He-4 hcp Crystals at Zero Temperature and Fixed Pressure
• Supersolid behavior in confined geometry
• Onset temperature of Bose-Einstein condensation in incommensurate solid 4He
• Quantum dislocations: the fate of multiple vacancies in two dimensional solid 4He
• Condensate fraction in liquid 4He at zero temperature
• Effects of ${}^3$He Impurity on Solid ${}^4$He Studied by Compound Torsional Oscillator
• Zero-point Divacancy Concentration in the Shadow Wave-Function Model for Solid 4He
• Josephson effects in one-dimensional supersolids
• Supersolid phase of Three-dimensional spin and hardcore-boson models
• Fermionic Shadow Wavefunction Variational calculations of the vacancy formation energy in ${}^3$He
• Study of solid 4He in two dimensions. The issue of zero-point defects and study of confined crystal
• Exact crystalline solution for a one-dimensional few-boson system with point interaction
• Linear response of one-dimensional liquid ${}^4$He to external perturbations
• Off-diagonal Long-Range Order and Supersolidity in a Quantum Solid with Vacancies
• Quantized vortex state in hcp solid 4He
• Superfluidity of a perfect quantum crystal