scholarly journals Heisenberg spins on an anisotropic triangular lattice: PdCrO2 under uniaxial stress

2021 ◽  
Author(s):  
Dan Sun ◽  
Dmitry Sokolov ◽  
Richard Waite ◽  
Seunghyun Khim ◽  
Pascal Manuel ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Triangular Lattice ◽  
Ground State ◽  
Nearest Neighbor ◽  
Magnetic Order ◽  
Uniaxial Stress ◽  
Rate Of Change ◽  
Resistivity Measurements ◽  
First Order ◽  
First Order Transition

Abstract When Heisenberg spins interact antiferromagnetically on a triangular lattice and nearest-neighbor interactions dominate, the ground state is 120◦ antiferromagnetism. In this work, we probe the response of this state to lifting the triangular symmetry, through investigation of the triangular antiferromagnet PdCrO2 under uniaxial stress by neutron diffraction and resistivity measurements. The periodicity of the magnetic order is found to change rapidly with applied stress; the rate of change indicates that the magnetic anisotropy is roughly forty times the stress-induced bond length anisotropy. At low stress, the incommensuration period becomes extremely long, on the order of 1000 lattice spacings; no locking of the magnetism to commensurate periodicity is detected. Separately, the magnetic structure is found to undergo a first-order transition at a compressive stress of ∼0.4 GPa, at which the interlayer ordering switches from a double- to a single-q structure.

scholarly journals Macroscopic degeneracy and order in the 3D plaquette Ising model

2015 ◽  
Vol 29 (20) ◽  
pp. 1550109 ◽  
Author(s):  
Desmond A. Johnston ◽  
Marco Mueller ◽  
Wolfhard Janke
Keyword(s):  
Low Temperature ◽  
Magnetic Order ◽  
Finite Size ◽  
Temperature Phase ◽  
Finite Size Scaling ◽  
First Order ◽  
Magnetic Order Parameter ◽  
First Order Transition ◽  
Definition Of ◽  
Low Temperature Phase

The purely plaquette 3D Ising Hamiltonian with the spins living at the vertices of a cubic lattice displays several interesting features. The symmetries of the model lead to a macroscopic degeneracy of the low-temperature phase and prevent the definition of a standard magnetic order parameter. Consideration of the strongly anisotropic limit of the model suggests that a layered, “fuki-nuke” order still exists and we confirm this with multi-canonical simulations. The macroscopic degeneracy of the low-temperature phase also changes the finite-size scaling corrections at the first-order transition in the model and we see this must be taken into account when analyzing our measurements.

A Monte Carlo and renormalization group study of the Ising model with nearest and next nearest neighbor interactions on the triangular lattice

1983 ◽  
Vol 61 (11) ◽  
pp. 1515-1527 ◽  
Author(s):  
James Glosli ◽  
Michael Plischke
Keyword(s):  
Monte Carlo ◽  
Renormalization Group ◽  
Ising Model ◽  
Potts Model ◽  
Triangular Lattice ◽  
Nearest Neighbor ◽  
Universality Class ◽  
Energy Functional ◽  
First Order ◽  
Universality Classes

The Ising model with nearest and next nearest neighbor antiferromagnetic interactions on the triangular lattice displays, for Jnnn/Jnn = 0.1, three phase transitions in different universality classes as the magnetic field is increased. We have studied this model using Monte Carlo and renormalization group techniques. The transition from the paramagnetic to the 2 × 1 phase (universality class of the Heisenberg model with cubic anisotropy) is found to be first order; the transition from the paramagnetic phase to the [Formula: see text] phase (universality class of the three state Potts model) is continuous; and the transition from the paramagnetic to the 2 × 2 phase (universality class of the four state Potts model) is found to change from first order to continuous as the field is increased. We have mapped out the phase diagram and determined the critical exponents for the continuous transitions. A novel technique, using a Landau-like free energy functional determined from Monte Carlo calculations, to distinguish between first order and continuous transitions, is described.

First-Order Transition in anxyModel with Nearest-Neighbor Interactions

1984 ◽  
Vol 52 (17) ◽  
pp. 1535-1538 ◽  
Author(s):  
Eytan Domany ◽  
Michael Schick ◽  
Robert H. Swendsen
Keyword(s):  
Nearest Neighbor ◽  
Order Transition ◽  
First Order ◽  
First Order Transition

scholarly journals Isoelectronic perturbations to f-d-electron hybridization and the enhancement of hidden order in URu2Si2

2021 ◽  
Vol 118 (20) ◽  
pp. e2026591118
Author(s):  
Christian T. Wolowiec ◽  
Noravee Kanchanavatee ◽  
Kevin Huang ◽  
Sheng Ran ◽  
Alexander J. Breindel ◽  
...  
Keyword(s):  
Tight Binding ◽  
External Pressure ◽  
Tight Binding Approximation ◽  
Electron States ◽  
Resistivity Measurements ◽  
First Order ◽  
Hidden Order ◽  
First Order Transition ◽  
Fe Substitution ◽  
Large Moment

Electrical resistivity measurements were performed on single crystals of URu2–xOsxSi2 up to x = 0.28 under hydrostatic pressure up to P = 2 GPa. As the Os concentration, x, is increased, 1) the lattice expands, creating an effective negative chemical pressure Pch(x); 2) the hidden-order (HO) phase is enhanced and the system is driven toward a large-moment antiferromagnetic (LMAFM) phase; and 3) less external pressure Pc is required to induce the HO→LMAFM phase transition. We compare the behavior of the T(x, P) phase boundary reported here for the URu2-xOsxSi2 system with previous reports of enhanced HO in URu2Si2 upon tuning with P or similarly in URu2–xFexSi2 upon tuning with positive Pch(x). It is noteworthy that pressure, Fe substitution, and Os substitution are the only known perturbations that enhance the HO phase and induce the first-order transition to the LMAFM phase in URu2Si2. We present a scenario in which the application of pressure or the isoelectronic substitution of Fe and Os ions for Ru results in an increase in the hybridization of the U-5f-electron and transition metal d-electron states which leads to electronic instability in the paramagnetic phase and the concurrent formation of HO (and LMAFM) in URu2Si2. Calculations in the tight-binding approximation are included to determine the strength of hybridization between the U-5f-electron states and the d-electron states of Ru and its isoelectronic Fe and Os substituents in URu2Si2.

scholarly journals Фазовая диаграмма модели Поттса с числом состояний спина q=4 на гексагональной решетке

2021 ◽  
Vol 63 (5) ◽  
pp. 622
Author(s):  
А.К. Муртазаев ◽  
М.К. Мазагаева ◽  
М.К. Рамазанов ◽  
М.А. Магомедов ◽  
А.А. Муртазаева
Keyword(s):  
Phase Transitions ◽  
Ground State ◽  
Nearest Neighbor ◽  
Hexagonal Lattice ◽  
Magnetic Ordering ◽  
Exchange Interactions ◽  
Antiferromagnetic Interaction ◽  
Two Dimensional ◽  
Magnetic Structures ◽  
First Order

We have carried out Monte Carlo investigations of the phase transitions, thermodynamic properties and ground-state magnetic structures in two-dimensional 4-state Potts model on a hexagonal lattice with the competing exchange interactions. Researches are carried out for the value of interaction of next-nearest neighbor in the range of 0.0≤r≤1.0. Taking into account of antiferromagnetic interaction of next-nearest neighbor is shown to lead to the violation of the magnetic ordering. The phase diagram of dependence of critical temperature on the value of interaction of next-nearest neighbor is plotted. Of the orders of phase transitions has been carried out. It is established that the phase transition of the first order is observed in the ranges of 0.0≤r≤0.2 and 0.7≤r≤1.0. In the range of 0.3≤r≤0.6 frustration are observed.

scholarly journals First-order antiferromagnetic transitions of SrMn2P2 and CaMn2P2 single crystals containing corrugated-honeycomb Mn sublattices

2021 ◽  
Vol 118 (44) ◽  
pp. e2108724118
Author(s):  
N. S. Sangeetha ◽  
Santanu Pakhira ◽  
Qing-Ping Ding ◽  
Lennard Krause ◽  
Hyung-Cheol Lee ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Magnetic Susceptibility ◽  
Single Crystals ◽  
Nearest Neighbor ◽  
Second Order ◽  
Magnetic Structures ◽  
First Order ◽  
Slowing Down ◽  
First Order Transition ◽  
Antiferromagnetic Transitions

SrMn2P2 and CaMn2P2 are insulators that adopt the trigonal CaAl2Si2-type structure containing corrugated Mn honeycomb layers. Magnetic susceptibility χ and heat capacity versus temperature T data reveal a weak first-order antiferromagnetic (AFM) transition at the Néel temperature TN=53(1) K for SrMn2P2 and a strong first-order AFM transition at TN=69.8(3) K for CaMn2P2. Both compounds exhibit isotropic and nearly T-independent χ(T≤TN), suggesting magnetic structures in which nearest-neighbor moments are aligned at ≈120° to each other. The 31P NMR measurements confirm the strong first-order transition in CaMn2P2 but show critical slowing down above TN for SrMn2P2, thus also evidencing second-order character. The 31P NMR measurements indicate that the AFM structure of CaMn2P2 is commensurate with the lattice whereas that of SrMn2P2 is incommensurate. These first-order AFM transitions are unique among the class of (Ca, Sr, Ba)Mn2 (P, As, Sb, Bi)2 compounds that otherwise exhibit second-order AFM transitions. This result challenges our understanding of the circumstances under which first-order AFM transitions occur.

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