scholarly journals High-temperature superconductivity and long-range order in strongly correlated electronic systems

2015 ◽  
Vol 115 (20) ◽  
pp. 1443-1458 ◽  
Author(s):  
Lawrence J. Dunne
Keyword(s):  
High Temperature ◽  
Long Range ◽  
High Temperature Superconductivity ◽  
Range Order ◽  
Electronic Systems ◽  
Long Range Order ◽  
Strongly Correlated ◽  
Strongly Correlated Electronic Systems

Strongly correlated transition metal oxides

2019 ◽  
Author(s):  
Ελένη Αζά
Keyword(s):  
Dielectric Permittivity ◽  
Single Crystal ◽  
Single Crystals ◽  
Long Range ◽  
Ground State ◽  
Degrees Of Freedom ◽  
Magnetic Order ◽  
Range Order ◽  
Long Range Order ◽  
Strongly Correlated

The discovery of materials with coexisting magnetic and ferroelectric orders, has revived theinterest of condensed matter physics and materials’ science communities maintaining the greatpromise of such fundamental mechanisms in devising applications ranging from portablemagnetoelectric (ME) sensors and memories to radar technologies. The present PhD thesis is a study in the field of strongly correlated systems where coupled properties arise from the interplay of charge and spin degrees of freedom over lattice topologies enabling competing magnetic interactions and therefore emergence of coupling of electric and magnetic order. Non-perovskite, two-dimensional (2D) Na-Mn-O oxides are revisited in scope of this in both polycrystalline and large single crystal forms. Among Na-deficient polymorphs, hexagonal α-Na0.7MnO2 (single crystals) has been investigated for the first time as a playground of competing interactions due to mixed Mnvalence (Mn4+ / Mn3+), fostered by Na vacancies in the structure. The competition of FM (Mn3+-Mn4+) and AFM (Mn3+ -Mn3+) interactions is believed to be the origin of the magnetic instability leading to a glassy ground state leaving also their footprint in the dielectric permittivity measurements. Competing FM and AFΜ interactions are also investigated as the origin of the anisotropic magnetic properties witnessed in a-NaxMnO2 (x= 0.96) single crystals. Neutron single crystal experiments show a well-established AFM long range order which vanishes above 26 K whilea coexistent canted antiferromagnetic state persists up to 45 K. In both alpha powders and aNa0.96MnO2 single crystals, the dielectric permittivity suggests the onset of the commensuratemagnetic long range order (T~ 45 K) which in the case of the powders allows a magnetocapacitance effect. Compositional modulations in β-NaMnO2, which are depicted as an intergrowth of α- and βlike oxygen coordinations, are found to trigger a proper-screw magnetic ground state which evolves into collinear commensurate AFM state. Features in the dielectric permittivity coincide with the onset of the commensurate AFM order giving away also the contribution of the α- structural domains. Further understanding of the mechanisms that dictate the relief of frustrated interactions and establishment of magnetic order together with the role of structural complexity in the form of domains or domain-walls is a direction that warrants further exploration as it will help us to resolve whether other coupled electron degrees of freedom are likely to be generated in this family of oxides.

Exact high temperature series expansions for the XY model

1970 ◽  
Vol 48 (13) ◽  
pp. 1566-1577 ◽  
Author(s):  
D. D. Betts ◽  
C. J. Elliott ◽  
M. H. Lee
Keyword(s):  
High Temperature ◽  
Long Range ◽  
Lattice Gas ◽  
Critical Index ◽  
Temperature Series ◽  
Range Order ◽  
Xy Model ◽  
Long Range Order ◽  
Critical Temperatures ◽  
Quantum Lattice Gas

A method is developed for the exact high temperature series expansion of thermodynamic properties of the spin 1/2 XY model of ferromagnetism or of a quantum lattice gas. Eleven coefficients in the specific heat series for the f.c.c. and b.c.c. lattices and nine coefficients in the series for the fluctuation in the long range order for the f.c.c., b.c.c., and s.c. lattices are calculated. From the fluctuation series the critical temperatures Kc−1 ≡ kTc/J are estimated to be 4.520, 2.902, and 2.02 respectively, while the critical index for the square of the fluctuation in the long range order is γ = 1.35.

ISING MODEL WITH STRONGLY CORRELATED RANDOM FIELDS

1988 ◽  
Vol 02 (10) ◽  
pp. 1137-1141 ◽  
Author(s):  
T. HORIGUCHI ◽  
L.L. GONCALVES
Keyword(s):  
Ising Model ◽  
Domain Wall ◽  
Long Range ◽  
Random Fields ◽  
Linear Chain ◽  
Ising Models ◽  
Range Order ◽  
Square Lattice ◽  
Long Range Order ◽  
Strongly Correlated

We investigate the Ising models with strongly correlated random fields, taking the values ±h0 and 0, on the square lattice and on the linear chain. The models present long range order and these results are consistent with the lower critical dimensionality obtained by the domain wall argument.

Measurement of Long Range Order in the γ’ Phase of Nickel-Base Superalloys

1969 ◽  
Vol 13 ◽  
pp. 598-608
Author(s):  
J.R. Mihalisin
Keyword(s):  
High Temperature ◽  
Long Range ◽  
Range Order ◽  
Long Range Order ◽  
X Ray Diffraction ◽  
High Temperature Heat Treatment ◽  
Heat Treated ◽  
Temperature Heat ◽  
Long Time ◽  
Nickel Base

The long range order parameter (S) has been measured at room- temperature on the γ’ phase extracted from IN-731 and alloys 713C and 713LC by x-ray diffraction techniques. Measurements were obtained from specimens of IN-731 and alloy 713LC in the as-cast condition and after long time rupture testing. The alloy 713 c specimens were in the as-cast and high temperature heat treated conditions.It was found that long range order in the γ’ phase of IN-731 and alloy 713LC was changed very little after long time rupture testing, and after high temperature heat treatment in the case of alloy 713C.

Long-range order in the high-temperature phase ofK2ZnCl4

1997 ◽  
Vol 56 (9) ◽  
pp. 5180-5185 ◽  
Author(s):  
F. X. Leduc ◽  
A. Hedoux ◽  
M. Descamps ◽  
F. Danede ◽  
G. Odou
Keyword(s):  
High Temperature ◽  
Long Range ◽  
High Temperature Phase ◽  
Range Order ◽  
Temperature Phase ◽  
Long Range Order

Determination of Short Range Order Parameters in 62Ni0.765Fe0.235 At 600°C Effect of a Quench

1982 ◽  
Vol 21 ◽  
Author(s):  
S. Lefebvre ◽  
F. Bley ◽  
P. Cenedese
Keyword(s):  
High Temperature ◽  
Long Range ◽  
Short Range ◽  
Room Temperature ◽  
Short Range Order ◽  
Range Order ◽  
Local Order ◽  
Long Range Order ◽  
Pair Potentials

ABSTRACTDifferent states of local order have been previously measured at room temperature on water quenched crystal of Ni0.76562 Fe0.235 [1−2]. The Cowley' parameters and the interaction pair potentials in a Clapp and floss approximation have been determined at : 385° C, 470°C, 507°C, 535°C, 685°C that is under and above Tc which is equal to 500°C for this composition.The kinetic of long range order establishment is, in this alloy, very sluggish even near Tc [3]; the kinetic of short range order (SRO) is completely different and may be more complex [4]. In the previous experiments it has been supposed that the state of high temperature was retained during the quench. The following experiments check this hypothesis.

Sign in / Sign up

Export Citation Format

Share Document