A Model of Two Quantum Fluids for the Low Energy Excited States of the Systems with Entities That Mimic the Magnetic Monopoles

The low energy excitation states in frustrated magnetic structures can generate quasiparticles that behave as if they were magnetic charges. These excited states produce, in the so-called spin-ice materials, two different peaks of specific heat at temperatures less than 1.5 K. In this paper, we consider that the first structure is caused by the formation of fluid of magnetic dipoles configured by the dumbbell model with a boson nature in consonance with that described by Witten for mesons. The second structure, wider than the first one, corresponds to a plasma state that comes from the breaking of a great number of dipoles, which provokes the appearance of free magnetic charges, which constitute a cool magnetic plasma fluid. In this paper, we determine thermodynamic analytical functions: the thermo-potential and internal energy and their respective derivative physical magnitudes: entropy, and magnetic specific heat. We obtain results in a good concordance with the experimental data, which allow us to explain the phase transitions occurred in these spin-ice materials at very low temperatures.

Download Full-text

“Color-Tripole Ice” as a Conceptual Generalization of “Spin Ice”

Journal of Materials ◽

10.1155/2013/836168 ◽

2013 ◽

Vol 2013 ◽

pp. 1-16 ◽

Cited By ~ 1

Author(s):

Chia-Ren Hu

Keyword(s):

High Energy Physics ◽

Zero Point ◽

High Energy ◽

Magnetic Monopoles ◽

Spin Ice ◽

Elementary Excitations ◽

Magnetic Dipoles ◽

Frustrated Magnet ◽

Statistical Mechanical ◽

Energy Physics

“Spin Ice” is an exotic type of frustrated magnet realized in “pyrochlore” materials Ho2Ti2O7, Dy2Ti2O7, Ho2Sn2O7, and so forth, in which magnetic atoms (spins) reside on a sublattice made of the vertices of corner-sharing tetrahedra. Each spin is Ising-like with respect to a local axis which connects the centers of two tetrahedra sharing the vertex occupied by the spin. The macroscopically degenerate ground states of these magnets obey the “two-in two-out” “ice rule” within each tetrahedron. Magnetic monopoles and antimonopoles emerge as elementary excitations, “fractionalizing” the constituent magnetic dipoles. This system is also a novel type of statistical mechanical system. Here we introduce a conceptual generalization of “spin ice” to what we shall call “color-tripole ice,” in which three types of “color charges” can emerge as elementary excitations, which are Abelian approximations of the color charges introduced in high energy physics. Two two-dimensional (2D) models are introduced first, where the color charges are found to be 1D and constrained 2D, respectively. Generalizations of these two models to 3D are then briefly discussed. In the second one the color charges are likely 3D. Pauling-type estimates of the “residual (or zero-point) entropy” are also made for these models.

Download Full-text

Two fluid model in low energy excited states within spin-ice systems

Scientific Reports ◽

10.1038/s41598-018-34529-x ◽

2018 ◽

Vol 8 (1) ◽

Author(s):

F. I. López-Bara ◽

F. López-Aguilar

Keyword(s):

Excited States ◽

Fluid Model ◽

Low Energy ◽

Spin Ice ◽

Two Fluid Model ◽

Two Fluid

Download Full-text

Analytic model for low energy excitation states and phase transitions in spin-ice systems

Journal of Physics Condensed Matter ◽

10.1088/1361-648x/aa5334 ◽

2017 ◽

Vol 29 (15) ◽

pp. 155803 ◽

Cited By ~ 1

Author(s):

F I López-Bara ◽

F López-Aguilar

Keyword(s):

Phase Transitions ◽

Low Energy ◽

Analytic Model ◽

Spin Ice ◽

Energy Excitation

Download Full-text

Influence of TOPO and TOPO-CdSe/ZnS Quantum Dots on Luminescence Photodynamics of InP/InAsP/InPHeterostructure Nanowires

Nanomaterials ◽

10.3390/nano11030640 ◽

2021 ◽

Vol 11 (3) ◽

pp. 640

Author(s):

Artem I. Khrebtov ◽

Vladimir V. Danilov ◽

Anastasia S. Kulagina ◽

Rodion R. Reznik ◽

Ivan D. Skurlov ◽

...

Keyword(s):

Quantum Dots ◽

Excited States ◽

Molecular Beam ◽

Surface Passivation ◽

Low Energy ◽

Trioctylphosphine Oxide ◽

Reverse Transfer ◽

Semiconductor Heterostructure ◽

Ligand Type

The passivation influence by ligands coverage with trioctylphosphine oxide (TOPO) and TOPO including colloidal CdSe/ZnS quantum dots (QDs) on optical properties of the semiconductor heterostructure, namely an array of InP nanowires (NWs) with InAsP nanoinsertion grown by Au-assisted molecular beam epitaxy on Si (111) substrates, was investigated. A significant dependence of the photoluminescence (PL) dynamics of the InAsP insertions on the ligand type was shown, which was associated with the changes in the excitation translation channels in the heterostructure. This change was caused by a different interaction of the ligand shells with the surface of InP NWs, which led to the formation of different interfacial low-energy states at the NW-ligand boundary, such as surface-localized antibonding orbitals and hybridized states that were energetically close to the radiating state and participate in the transfer of excitation. It was shown that the quenching of excited states associated with the capture of excitation to interfacial low-energy traps was compensated by the increasing role of the “reverse transfer” mechanism. As a result, the effectiveness of TOPO-CdSe/ZnS QDs as a novel surface passivation coating was demonstrated.

Download Full-text