Related papers: Experimental evidence for a second hydrogen ordere…
We map the high-pressure phase diagram of nitrogen hydrate up to 16 GPa at room temperature by combining neutron diffraction, Raman spectroscopy, and crystal structure prediction. We reveal a rich sequence of structural transformations,…
We have studied the Tb$_2$Sn$_2$O$_7$ frustrated magnet by neutron diffraction under isotropic pressure of 4.6 GPa, combined with uniaxial pressure of 0.3 GPa, in the temperature range 0.06 K$<$T$<$100 K. Magnetic order persists under…
Ice Ih, the common form of ice in the biosphere, contains proton disorder. Its proton-ordered counterpart, ice XI, is thermodynamically stable below 72 K. However, even below this temperature the formation of ice XI is kinetically hindered…
Polar liquid crystals possess three dimensional orientational order coupled with unidirectional electric polarity, yielding fluid ferroelectrics. Such polar phases are generated by rod-like molecules with large electric dipole moments.…
The recent discovery of a low-temperature endotherm upon heating hydrochloric-acid doped ice VI has sparked a vivid controversy. The two competing explanations aiming to explain its origin range from a new distinct crystalline phase of ice…
We discuss the problem of proton motion in Hydrogen bond materials with special focus on ice. We show that phenomenological models proposed in the past for the study of ice can be recast in terms of microscopic models in close relationship…
Motivated by recent neutron scattering experiments, we study the ordering of spins in the iron-based superconductors La(O_{1-x}F_x)FeAs, assuming them in proximity to a Mott insulator in the phase diagram. The ground state of the parent…
We employ classical molecular dynamics simulations to investigate the molecular-level structure of water during the isothermal compression of hexagonal ice (I$h$) and low-density amorphous (LDA) ice at low temperatures. In both cases, the…
High energy x-ray diffraction is used to investigate the bulk oxygen ordering properties of YBa_2Cu_3O_{6+x}. Superstructures of Cu-O chains aligned along the b axis and ordered with periodicity ma, along the a axis have been observed. For…
Most experimentally known high-pressure ice phases have a body-centred cubic (bcc) oxygen lattice. Our atomistic simulations show that, amongst these bcc ice phases, ices VII, VII' and X are the same thermodynamic phase under different…
Inspired by the stable bilayer water ice grown in the laboratory (Nature 577, 60, 2020), we propose a model representing water ice as a two-layer six-vertex model. Using the loop update Monte Carlo method, we unveil meaningful findings.…
We study the phase equilibrium between liquid water and ice Ih modeled by the TIP4P/Ice interatomic potential using enhanced sampling molecular dynamics simulations. Our approach is based on the calculation of ice Ih-liquid free energy…
Recent advances in cold atom experimentation suggest that studies of quantum two-dimensional melting of dipolar molecules, with dipoles aligned perpendicular to ordering plane, may be on the horizon. An intriguing aspect of this problem is…
The selection of stacking order in a broad range of close-packed polymorphic materials remains a challenging enigma. Using in situ cryogenic transmission electron microscopy, we uncover the atomistic mechanisms governing the vapour…
The structure of very high-density amorphous (VHDA) ice has been modelled by positionally disordering three crystalline phases, namely ice IV, VI and XII. These phases were chosen because only they are stable or metastable in the region of…
Under high pressure, Zr undergoes a transformation from its ambient equilibrium hexagonal close packed $\alpha$ phase to a simple hexagonal $\omega$ phase. Subsequent unloading to ambient conditions does not see a full reversal to the…
We present numerical studies of dipolar spin ice in the presence of a magnetic field slightly tilted away from the [111] axis. We find a first-order transition from a kagome ice to a $\mathbf{q}=$X state when the external field is tilted…
Despite water is the most studied substance in the Earth, it is not completely understood why its structural and dynamical properties give rise to some anomalous behaviors. Interesting properties emerge when experiments at low temperatures…
Under high pressure conditions, Zr undergoes a phase transformation from its ambient equilibrium hexagonal close packed $\alpha$ phase to hexagonal $\omega$ phase. Upon returning to ambient conditions, the material displays hysteretic…
We report a detailed ab initio investigation on the optical properties of ice under a wide high pressure range. The ice X phase (up to 380GPa), the theoretical proposed higher pressure phase ice XV (300GPa), as well as the ambient pressure…