scholarly journals Tc and Other Cuprate Properties in Relation to Planar Charges as Measured by NMR

2019 ◽  
Vol 4 (3) ◽  
pp. 67 ◽  
Author(s):  
Michael Jurkutat ◽  
Andreas Erb ◽  
Jürgen Haase
Keyword(s):  
Phase Diagram ◽  
Nuclear Magnetic Resonance ◽  
Low Temperatures ◽  
Quantitative Measure ◽  
Charge Order ◽  
Two Dimensional ◽  
Theoretical Understanding ◽  
Material Chemistry ◽  
Local Charge ◽  
Underdoped Cuprates

Nuclear magnetic resonance (NMR) in cuprate research is a prominent bulk local probe of magnetic properties. NMR also, as was shown over the last years, actually provides a quantitative measure of local charges in the CuO 2 plane. This has led to fundamental insights, e.g., that the maximum T c is determined by the sharing of the parent planar hole between Cu and O. Using bonding orbital hole contents on planar Cu and O measured by NMR, instead of the total doping x, the thus defined two-dimensional cuprate phase diagram reveals significant differences between the various cuprate materials. Even more importantly, the reflected differences in material chemistry appear to set a number of electronic properties as we discuss here, for undoped, underdoped and optimally doped cuprates. These relations should advise attempts at a theoretical understanding of cuprate physics as well as inspire material chemists towards new high- T c materials. Probing planar charges, NMR is also sensitive to charge variations or ordering phenomena in the CuO 2 plane. Thereby, local charge order on planar O in optimally doped YBCO could recently be proven. Charge density variations seen by NMR in both planar bonding orbitals with amplitudes between 1% to 5% appear to be omnipresent in the doped CuO 2 plane, i.e., not limited to underdoped cuprates and low temperatures.

Out-of-Plane and in-Plane Conduction in Insulating and Strongly Underdoped Cuprates

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3203-3206
Author(s):  
C. C. Almasan ◽  
G. A. Levin ◽  
E. Cimpoiasu ◽  
T. Stein ◽  
D. A. Gajewski ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Normal State ◽  
Low Temperatures ◽  
Elementary Step ◽  
Charge Carriers ◽  
Two Dimensional ◽  
Out Of Plane ◽  
Underdoped Cuprates

We report measurements of out-of-plane (ρ c ) and in-plane (ρab) normal-state resistivities of single crystals of insulating PrBa2Cu3O 7-δ and strongly underdoped oxygen deficient YBa2Cu3O 6.41 using a flux transformer method. In the superconducting specimens, the onset of superconductivity was suppressed by a magnetic field of 9 T. We have found that the anisotropy ρc/ρab of these samples increases monotonically at low temperatures with no signs of saturation. The temperature dependence of ρc/ρab for YBa2Cu3O6.41 is well described by ρc/ρab=a +bT-2/3, but over a smaller temperature range than for insulating PrBa2Cu3O 7-δ. Both the absence of saturation of ρc/ρab and its T-2/3 dependence indicate two-dimensional conduction. This means that the average in-plane hopping distance of the localized charge carriers increases with decreasing T according to Mott's [Formula: see text] law, while the elementary step in the c-direction remains T independent, equal to the spacing between the bilayers.

scholarly journals Entropy, Information, and Symmetry: Ordered is Symmetrical

Entropy ◽  
2019 ◽  
Vol 22 (1) ◽  
pp. 11 ◽  
Author(s):  
Edward Bormashenko
Keyword(s):  
Binary System ◽  
Physical System ◽  
Quantitative Measure ◽  
2D Systems ◽  
Two Dimensional ◽  
One Dimensional ◽  
Entropy Information

Entropy is usually understood as the quantitative measure of “chaos” or “disorder”. However, the notions of “chaos” and “disorder” are definitely obscure. This leads to numerous misinterpretations of entropy. We propose to see the disorder as an absence of symmetry and to identify “ordering” with symmetrizing of a physical system; in other words, introducing the elements of symmetry into an initially disordered physical system. We demonstrate with the binary system of elementary magnets that introducing elements of symmetry necessarily diminishes its entropy. This is true for one-dimensional (1D) and two-dimensional (2D) systems of elementary magnets. Imposing symmetry does not influence the Landauer principle valid for the addressed systems. Imposing the symmetry restrictions onto the system built of particles contained within the chamber divided by the permeable partition also diminishes its entropy.

Rotational diffusion measurements of suspended colloidal particles using two‐dimensional exchange nuclear magnetic resonance

1996 ◽  
Vol 104 (2) ◽  
pp. 509-520 ◽  
Author(s):  
G. A. Barrall ◽  
K. Schmidt‐Rohr ◽  
Y. K. Lee ◽  
K. Landfester ◽  
H. Zimmermann ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Colloidal Particles ◽  
Rotational Diffusion ◽  
Two Dimensional ◽  
Nuclear Magnetic

Specific heat of ordered and isotopically disordered lattices

1978 ◽  
Vol 56 (10) ◽  
pp. 1390-1394
Author(s):  
K. P. Srivastava
Keyword(s):  
Specific Heat ◽  
Low Temperatures ◽  
Numerical Study ◽  
Three Dimensional ◽  
Constant Volume ◽  
Nearest Neighbour ◽  
Two Dimensional ◽  
Appreciable Difference ◽  
Substantial Change ◽  
Neighbour Interaction

An extensive numerical study on specific heat at constant volume (Cv) for ordered and isotopically disordered lattices has been made. Cv at various temperatures for ordered and disordered linear and two-dimensional lattices have been compared and no appreciable difference in Cv between these two structures has been observed. Effect of concentration of light atoms on Cv for three-dimensional isotopically disordered lattices has also been shown.In spite of taking next-nearest-neighbour interaction into account, no substantial change in Cv between the ordered and isotopically disordered linear lattices has been found. It is shown that the low lying modes contribute substantially at low temperatures.

COMPLEX BIFURCATION STRUCTURES IN THE HINDMARSH–ROSE NEURON MODEL

2007 ◽  
Vol 17 (09) ◽  
pp. 3071-3083 ◽  
Author(s):  
J. M. GONZÀLEZ-MIRANDA
Keyword(s):  
Phase Diagram ◽  
Bifurcation Diagram ◽  
Parameter Space ◽  
Neuron Model ◽  
Two Dimensional ◽  
Dimensional Parameter ◽  
Rapid Responses ◽  
Bifurcation Structures

The results of a study of the bifurcation diagram of the Hindmarsh–Rose neuron model in a two-dimensional parameter space are reported. This diagram shows the existence and extent of complex bifurcation structures that might be useful to understand the mechanisms used by the neurons to encode information and give rapid responses to stimulus. Moreover, the information contained in this phase diagram provides a background to develop our understanding of the dynamics of interacting neurons.

scholarly journals Universal behavior of the bosonic metallic ground state in a two-dimensional superconductor

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Zhuoyu Chen ◽  
Bai Yang Wang ◽  
Adrian G. Swartz ◽  
Hyeok Yoon ◽  
Yasuyuki Hikita ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Phase Diagram ◽  
Quantum Phase Transitions ◽  
Metallic State ◽  
Two Dimensional ◽  
Metallic Behavior ◽  
Universal Behavior ◽  
Hall Resistivity ◽  
Wide Range ◽  
Metal State

AbstractAnomalous metallic behavior, marked by a saturating finite resistivity much lower than the Drude estimate, has been observed in a wide range of two-dimensional superconductors. Utilizing the electrostatically gated LaAlO3/SrTiO3 interface as a versatile platform for superconductor-metal quantum phase transitions, we probe variations in the gate, magnetic field, and temperature to construct a phase diagram crossing from superconductor, anomalous metal, vortex liquid, to the Drude metal state, combining longitudinal and Hall resistivity measurements. We find that the anomalous metal phases induced by gating and magnetic field, although differing in symmetry, are connected in the phase diagram and exhibit similar magnetic field response approaching zero temperature. Namely, within a finite regime of the anomalous metal state, the longitudinal resistivity linearly depends on the field while the Hall resistivity diminishes, indicating an emergent particle-hole symmetry. The universal behavior highlights the uniqueness of the quantum bosonic metallic state, distinct from bosonic insulators and vortex liquids.

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