相关论文: Rigid unit modes in tetrahedral crystals
For a high-quality single crystal of UPd_3 we present the relevant elastic constants and ultrasonic attenuation data. In addition to the magnetic phase transition at T_2=4.4 +/- 0.1K and the quadrupolar transition at T_1~6.8K, we find…
A first-principles atomic orbital-based electronic structure method is used to investigate the low index surfaces of rutile Titanium Dioxide. The method is relatively cheap in computational terms, making it attractive for the study of oxide…
We study equilibrium properties of a system of particles in two dimensions, interacting with pair and three body potentials, which undergoes a structural transition from a square to a rhombic lattice and thus constitutes a simple model for…
It is shown that tiling in icosahedral quasicrystals can also be properly described by cyclic twinning at the unit cell level. The twinning operation is applied on the primitive prolate golden rhombohedra, which can be considered a result…
We present the first unquenched, continuum limit, lattice QCD results for the matrix elements of the operators describing neutral kaon oscillations in extensions of the Standard Model. Owing to the accuracy of our calculation on \Delta S=2…
In this work we apply the density matrices approach to orbital ordering (OO) in order to study the OO of the spinel vanadates AV$_{2}$O$_{4}$ (A $\equiv$ Zn, Cd and Mg), which is normally believed to be responsible for the structural…
Standing light waves structure the electronic density of a Rydberg atom in a rich but surprisingly systematic fashion. We uncover these systematics, which are nearly universal across a large range of principal quantum numbers n, by varying…
Recent formal classifications of crystalline topological insulators predict that the combination of time-reversal and rotational symmetry gives rise to topological invariants beyond the ones known for other lattice symmetries. Although the…
Using synchrotron X-rays and neutron diffraction we disentangle spin-lattice order in highly frustrated ZnCr$_2$O$_4$ where magnetic chromium ions occupy the vertices of regular tetrahedra. Upon cooling below 12.5 K the quandary of…
We use single-crystal neutron diffraction to determine the crystal structure symmetry and the magnetic evolution in the rhodium doped iridates $\rm Sr_2Ir_{1-x}Rh_{x}O_4$ ($0\leq x \leq 0.16$). Throughout this doping range, the crystal…
A central question in dynamics is whether the topology of a system determines its geometry. This is known as rigidity. Under mild topological conditions rigidity holds for many classical cases, including: Kleinian groups, circle…
Using first-principles density functional theory calculations, we discover an anomalously large bi-axial strain-induced octahedral rotation axis reorientation in orthorhombic perovskites with tendency towards rhombohedral symmetry. The…
We consider a column of a rotating stationary surface in Euclidean space. We obtain a value $l_0>0$ in such way that if the length $l$ of column satisfies $l>l_0$, then the surface is instable. This extends, in some sense, previous results…
Restructuring of rutile TiO$_{2}$ under electron beam irradiation driven by radiolysis was observed and analyzed using a combination of atomic-resolution imaging and electron energy loss spectroscopy (EELS) in scanning transmission electron…
Structure factors for Cax/2AlxSi1-xO2 glasses (x=0,0.25,0.5,0.67) extended to a wave vector of magnitude Q= 40 1/A have been obtained by high-energy x-ray diffraction. For the first time, it is possible to resolve the contributions of Si-O,…
We report temperature and thermal-cycling dependence of surface and bulk structures of double-layered perovskite Sr3Ru2O7 single crystals. The surface and bulk structures were investigated using low-energy electron diffraction (LEED) and…
We have developed a 3D version for the Modulated Spin Liquid in a body-centered tetragonal lattice structure to describe the hidden order observed in URu$_2$Si$_2$ at $T_0\approx17.5$ K. This second order transition is well described by our…
RuO$_2$ was considered for a long time to be a paramagnetic metal with an ideal rutile-type structure down to low temperatures, but recent studies on single-crystals claimed evidence for antiferromagnetic order and some symmetry breaking in…
Contrary to canonical expectations we show that lattice translational symmetry breaking often accompanies uniformly ordered flux phases. We demonstrate this phenomena by studying a spinless-fermion model on a square latttice with…
Strongly anisotropic spin-orbit coupling (SOC) renormalization and strongly enhanced orbital magnetic moments are obtained in the fully self consistent approach including the orbital off-diagonal spin and charge condensates. For moderate…