scholarly journals Exploration of magnetism in 3D and 2D systems

2019 ◽  
Author(s):  
◽  
Ashutosh Dahal
Keyword(s):  
Phase Transition ◽  
Magnetic Properties ◽  
Low Temperature ◽  
Data Storage ◽  
Measurement Techniques ◽  
Honeycomb Lattice ◽  
Synthesis Methods ◽  
Detailed Knowledge ◽  
Two Dimensional ◽  
Magnetic Fluctuations

Magnetism has intruded in every aspect of our life, from electric motors to hard disk data storage to space technologies. Developing strong understanding of underlying magnetic properties is of utmost importance to reach new frontiers of technological advancement. During my Ph.D. research, I have explored complementary research venues in three dimensional as well as two dimensional materials to understand basic magnetic properties that were either not known or explored for the first time. In this quest, I have studied three different physical systems with overlapping structural and/or magnetic and electrical properties: nickel monosilicides (NiSi), cobalt-doped calcium ruthenate (Ca(CoxRu1-x)O3) and europium manganese arsenide (EuMn2As2). One of the key aspects of my research is to understand how magnetic moments correlate with each other. Understanding this fundamental question can help us in elucidating the mechanism behind novel magnetic proper-ties manifested by the above mentioned materials. While NiSi is found to manifest a new phenomenon of magnetism driven intermediate metallic-superconducting phase, (Ca(CoxRu1-x)O3) tends to exhibit the metal-insulator transition with the critical phase boundary coinciding with the onset of strong continuum type magnetic fluctuations. Despite the presence of strong dynamic magnetic moment correlation, no trace of any type of static magnetic order is detected in any of these materials. On the other hand, strong static order with two consecutive antiferromagnetic phase transitions are detected in the intertwined honeycomb structured EuMn2As2. During the process of studying bulk materials using macroscopic measurement techniques, I have acquired detailed knowledge of chemical synthesis methods and several experimental measurement techniques, including the analysis of magnetic susceptibility and neutron scattering methods. The gained knowledge is applied in pinpointing the low temperature magnetic phase transition in an ongoing project in the lab of two dimensional artificial magnetic (permalloy) honeycomb lattice. Two dimensional magnetic honeycomb lattice provides a unique platform to study emergent magnetic phenomena in reduced degrees of freedom. The system is expected to develop novel spin solid order at low temperature. I have performed detailed analysis of non-linear susceptibility of permalloy honeycomb lattice, which revealed the non-thermodynamic nature of phase transition to the spin solid state in this system. In the ensuing chapters, I have explained each project in great detail. A brief overview of the previous research works and the motivations behind the study is provided in the Introduction section.

scholarly journals The Research on the Complexity of 1T-TaS2 at Ultra-low Temperatures

2022 ◽  
Vol 2152 (1) ◽  
pp. 012002
Author(s):  
Tianxue Han
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Density Wave ◽  
Transition Metal Dichalcogenide ◽  
Two Dimensional ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Two Dimensional Materials ◽  
Metal Evaporation ◽  
Metal Phase Transition

Abstract Graphene, as a successfully industrialized two-dimensional material, has greatly promoted the development of other two-dimensional materials, such as transition metal dichalcogenide (TMDs). 1T-TaS2 is a classical TMDs material, which presents metallicity at high temperature. It undergoes a variety of charge density wave (CDW) phase transitions during the temperature declining process, and presents insulating properties at low temperature. During the temperature rise period, 1T-TaS2 goes through a phase transition, from an energy band insulator to Mott insulator, followed by an insulation-metal phase transition. The complexity of 1T-TaS2 phase diagram encourages researchers to conduct extensive research on it. This paper, via means of resistance, magnetic susceptibility and other technical methods, finds out that the ultra-low temperature of 1T-TaS2 suggests additional complexity. In addition, with the angle resolved photoemission spectroscopy (ARPES) technique of in-situ alkali metal evaporation, this paper proposes that the 1T-TaS2 ultra-low temperature ground state may exist a combination of state and surface state. Our findings provide more experimental evidence for the physical mechanism of this system.

Low-temperature magnetic properties of a two-dimensional spin nematic state

1991 ◽  
Vol 3 (19) ◽  
pp. 3353-3366 ◽  
Author(s):  
A A Nersesyan ◽  
G I Japaridze ◽  
I G Kimeridze
Keyword(s):  
Magnetic Properties ◽  
Low Temperature ◽  
Two Dimensional ◽  
Nematic State

scholarly journals Magnetic properties of two-dimensional nanodots: Ground state and phase transition

AIP Advances ◽  
2013 ◽  
Vol 3 (12) ◽  
pp. 122121 ◽  
Author(s):  
Maciej Kasperski ◽  
Henryk Puszkarski ◽  
Danh-Tai Hoang ◽  
H. T. Diep
Keyword(s):  
Phase Transition ◽  
Magnetic Properties ◽  
Ground State ◽  
Two Dimensional

Strain-driven Phase Transition and Spin Polarization of Re-doped Transition-Metal Dichalcogenides

2021 ◽  
Author(s):  
Ruining Wang ◽  
Chen-Dong Jin ◽  
Hu Zhang ◽  
Ru-Qian Lian ◽  
Xingqiang Shi ◽  
...  
Keyword(s):  
Phase Transition ◽  
Magnetic Properties ◽  
Transition Metal ◽  
Spin Polarization ◽  
Transition Metal Dichalcogenides ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Two Dimensional ◽  
Energy Landscapes ◽  
Metal Dichalcogenides

Two-dimensional transition metal dichalcogenides (TMDCs) are promising in spintronics due to their spin-orbit coupling, but the intrinsic non-magnetic properties limit their further developments. Here, we focus on the energy landscapes...

scholarly journals Terahertz optics-driven phase transition in two-dimensional multiferroics

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Jian Zhou ◽  
Shunhong Zhang
Keyword(s):  
Phase Transition ◽  
Data Storage ◽  
Transition Process ◽  
Ferroelectric Materials ◽  
Two Dimensional ◽  
Phonon Modes ◽  
Switching Speed ◽  
Strongly Coupled ◽  
Mechanical Responses ◽  
Ferroic Materials

AbstractDisplacive martensitic phase transition is potentially promising in semiconductor-based data storage applications with fast switching speed. In addition to traditional phase transition materials, the recently discovered two-dimensional ferroic materials are receiving a lot of attention owing to their fast ferroic switching dynamics, which could tremendously boost data storage density and enhance read/write speed. In this study, we propose that a terahertz laser with an intermediate intensity and selected frequency can trigger ferroic order switching in two-dimensional multiferroics, which is a damage-free noncontacting approach. Through first-principles calculations, we theoretically and computationally investigate optically induced electronic, phononic, and mechanical responses of two experimentally fabricated multiferroic (with both ferroelastic and ferroelectric) materials, β-GeSe and α-SnTe monolayer. We show that the relative stability of different orientation variants can be effectively manipulated via the polarization direction of the terahertz laser, which is selectively and strongly coupled with the transverse optical phonon modes. The transition from one orientation variant to another can be barrierless, indicating ultrafast transition kinetics and the conventional nucleation-growth phase transition process can be avoidable.

Low-temperature phase transition and magnetic properties of K3YbSi2O7

2021 ◽  
Vol 77 (4) ◽  
Author(s):  
Predrag Dabić ◽  
Volker Kahlenberg ◽  
Biljana Krüger ◽  
Marko Rodić ◽  
Sabina Kovač ◽  
...  
Keyword(s):  
Phase Transition ◽  
Magnetic Properties ◽  
Phase Transformation ◽  
Low Temperature ◽  
Orthorhombic Phase ◽  
Temperature Phase ◽  
Space Group ◽  
Temperature Phase Transition ◽  
New Type ◽  
Low Temperature Phase

The new ambient-temperature hexagonal (space group P63 /mmc) polymorph of tripotassium ytterbium(III) disilicate (β-K3YbSi2O7) has been synthesized by the high-temperature flux method and subsequently structurally characterized. In the course of the temperature-dependent single-crystal diffraction experiments, a phase transformation of β-K3YbSi2O7 to a novel low-temperature orthorhombic phase (β′-K3YbSi2O7, space group Cmcm) has been observed at about 210 K. β-K3YbSi2O7 is isostructural with K3ErSi2O7, whereas β′-K3YbSi2O7 adopts a new type of structure. Both compounds can be built up from a regular alternation of layers of two types, which are parallel to the (001) plane. In the octahedral layer, YbO6 octahedra are isolated and linked by K1O6+3 polyhedra. The second, slightly thicker sorosilicate layer is formed by a combination of Si2O7 dimers and K2O6+3 polyhedra. The boundary between the layers is a pseudo-kagome oxide sheet based on 3.6.3.6 meshes. The phase transition is due to a tilt of the two SiO4 tetrahedra forming a single dimer which induces a decrease of the Si—O—Si angle between bridging Si—O bonds from 180° (dictated by symmetry in space group P63/mmc) to ≃164°. Magnetic characterization indicates that K3YbSi2O7 remains paramagnetic down to 2 K, showing no apparent influence of the phase transformation on its magnetic properties. Analysis of the magnetization data revealed the positions of the three lowest crystal field levels of the Yb3+ cations, as well as the corresponding projections of their angular momentum on the direction of the magnetic field.

Transport Properties of Normal and Quasinormal States of Poor Superconductors

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3151-3156 ◽  
Author(s):  
Vsevolod Gantmakher
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Low Temperature ◽  
Single Crystals ◽  
Quantum Phase Transition ◽  
Normal State ◽  
Cooper Pairs ◽  
Two Dimensional ◽  
Field State ◽  
The Magnetic Field

There are some doubts whether materials near the superconductor–insulator transition (SIT), either on the insulating side, or with superconductivity suppressed by the magnetic field, behave like an ordinary metal. Two experiments in which this issue is addressed will be reviewed here, namely, transport measurements of two different materials: single crystals YBa2Cu3O 6+x (x ≈ 0.37) — a representative of the HTS family and amorphous InO x where x is the oxygen content which could be changed through moderate-temperature annealing. The low-temperature normal resistivity ρ(T) of YBaCuO crystals on both sides of SIT behaves as usual "bad" metal with conductivity below the Mott's minimum value. The amorphous In-O films behave differently. Those films with superconductivity do not display any characteristic magnetic field which can be interpreted as Bc2. Instead, they give out an example of a quantum phase transition and follow Fisher's model1 for "the field-tuned SIT in disordered two-dimensional superconductors" though they are not precisely two-dimensional and their high-magnetic-field state may not be insulating at all. Apparently, the normal state of InO x films comprises localized Cooper pairs.

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