The hexatic phase is a state of matter that is between the solid and the isotropic liquid phases in two dimensional systems of particles. It is characterized by two order parameters: a short-range positional and a quasi-long-range orientational (sixfold) order. More generally, a hexatic is any phase that contains sixfold orientational order, in analogy with the nematic phase (with twofold orientational order).
It is a fluid phase, since the shear modulus and the Young's modulus vanish due to the dissociation of dislocations. It is an anisotropic phase, since there exists a director field with sixfold symmetry. The existence of the director field implies that an elastic modulus against drilling or torsion exists within the plane, that is usually called Frank's constant after Frederick C. Frank in analogy to liquid crystals. The ensemble becomes an isotropic liquid (and Frank's constant becomes zero) after the dissociation of disclinations at a higher temperature (or lower density). Therefore, the hexatic phase contains dislocations but no disclinations.
The KTHNY theory of two-step melting by i) destroying positional order and ii) destroying orientational order was developed by John Michael Kosterlitz, David J. Thouless, Bertrand Halperin, David Robert Nelson and A. P. Young in theoretical studies about topological defect unbinding two dimensions. In 2016, M. Kosterlitz and D. Thouless were awarded with the Nobel prize in physics (together with Duncan Haldane) for the idea that melting in 2D is mediated by topological defects. The hexatic phase was predicted by D. Nelson and B. Halperin; it does not have a strict analogue in three dimensions.
The hexaticphase is a state of matter that is between the solid and the isotropic liquid phases in two dimensional systems of particles. It is characterized...
dislocations, indicating a fluid phase. Based on this work, David Nelson and Bertrand Halperin showed, that the resulting hexaticphase is not yet an isotropic...
Nelson, worked out a theory of two-dimensional melting, predicting the hexaticphase before it was experimentally observed by Pindak et al. In the 1980s...
of concentration and molecular weight, DNA will form an achiral line hexaticphase. An interesting recent observation is of the formation of chiral mesophases...
disclinations store elastic energy by disturbing the director field. Hexaticphase Volterra, Vito (1907). "Sur l'équilibre des corps élastiques multiplement...
fluid phase with typically a six-folded director field. This so-called hexaticphase still has an orientational stiffness. The isotropic fluid phase appears...
a crystalline phase of low-density electrons. Hexatic state, a state of matter that is between the solid and the isotropic liquid phases in two dimensional...
existence of an equilibrium hexaticphase as well as a strongly first-order liquid-to-hexatic and hexatic-to-solid phase transition. These observations...
two-dimensional melting that predicted a fourth "hexatic" phase of matter, interposed between the usual solid and liquid phases. A variety of predictions associated...
(September 2020). "Melting of a skyrmion lattice to a skyrmion liquid via a hexaticphase". Nature Nanotechnology. 15 (9): 761–767. arXiv:1807.08352. Bibcode:2020NatNa...
coworkers discovered the line hexaticphase in the phase diagram of the concentrated long fragment DNA solutions [1]. The line hexatic mesophase appears to be...
of symmetry, e.g. superfluid helium, hexatic liquid crystals. This is what makes them peculiar from other phase transitions which are always accompanied...
M. Chudnovsky, "Hexatic vortex glass in disordered superconductors", Physical Review B 40, 11355 (1989)]. E. M. Chudnovsky, "Phase transitions in the...
spin-glass model. Finally it introduces a continuum elastic theory for certain hexatic molecules. During his Ph.D studies he briefly interned at the Bell Labs...
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