scholarly journals From hidden metal-insulator transition to Planckian-like dissipation by tuning the oxygen content in a nickelate

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Qikai Guo ◽  
Beatriz Noheda
Keyword(s):  
Oxygen Content ◽  
Fluid Model ◽  
Insulator Transition ◽  
Metallic State ◽  
Linear Temperature Dependence ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Linear Temperature ◽  
Scattering Rate ◽  
Two Fluid Model

AbstractHeavily oxygen-deficient NdNiO3 (NNO) films, which are insulating due to electron localization, contain pristine regions that undergo a hidden metal-insulator transition. Increasing oxygen content increases the connectivity of the metallic regions and the metal-insulator transition is first revealed, upon reaching the percolation threshold, by the presence of hysteresis. Only upon further oxygenation is the global metallic state (with a change in the resistivity slope) eventually achieved. It is shown that sufficient oxygenation leads to linear temperature dependence of resistivity in the metallic state, with a scattering rate directly proportional to temperature. Despite the known difficulties to establish the proportionality constant, the experiments are consistent with a relationship 1/τ = αkBT/ℏ, with α not far from unity. These results could provide experimental support for recent theoretical predictions of disorder in a two-fluid model as a possible origin of Planckian dissipation.

scholarly journals Identification of a monoclinic metallic state in VO2 from a modified first-principles approach

2019 ◽  
Vol 33 (12) ◽  
pp. 1950148
Author(s):  
Yongcheng Liang ◽  
Ping Qin ◽  
Zhiyong Liang ◽  
Lizhen Zhang ◽  
Xun Yuan ◽  
...  
Keyword(s):  
First Principles ◽  
Lattice Distortion ◽  
Insulator Transition ◽  
Metallic State ◽  
Strongly Correlated ◽  
Electron Systems ◽  
First Principles Calculations ◽  
Monoclinic Structure ◽  
Metal Insulator Transition ◽  
Metal Insulator

Metal-insulator transition (MIT) underlies many remarkable and technologically important phenomena in VO2. Even though its monoclinic structure had before been the reserve of the insulating state, recent experiments have observed an unexpected monoclinic metallic state. Here, we use a modified approach combining first-principles calculations with orbital-biased potentials to reproduce the correct stability ordering and electronic structures of different phases of VO2. We identify a ferromagnetic monoclinic metal that is likely to be the experimentally observed mysterious metastable state. Furthermore, the calculations show that an isostructural insulator-metal electronic transition is followed by the lattice distortion from the monoclinic structure to the rutile one. These results not only explain the experimental observations of the monoclinic metallic state and the decoupled structural and electronic transitions of VO2, but also provide a useful understanding for the metal-insulator transition in other strongly correlated d electron systems.

HIGH PRESSURE STUDY OF NOVEL ELECTRONIC PROPERTIES IN Sr2Fe(W1-xMox)O6 NEAR METAL-INSULATOR TRANSITION

2007 ◽  
Vol 21 (18n19) ◽  
pp. 3279-3284
Author(s):  
G. OOMI ◽  
S. KAJI ◽  
Y. TOMIOKA ◽  
Y. TOKURA
Keyword(s):  
High Pressure ◽  
Double Perovskite ◽  
Insulator Transition ◽  
Metallic State ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Electrical Resistivities ◽  
Insulating Properties ◽  
High Pressure Study ◽  
Variable Range Hopping Conduction

Electrical resistivities of double perovskite oxides Sr 2 Fe ( W 1-x Mo x) O 6 have been measured at high pressure and high magnetic field to elucidate the transport properties of these materials. It is found that the main mechanism of the transport in the semiconducting phase is variable range hopping conduction and the insulating properties are suppressed by high pressure to show a crossover to metallic state. The magnetoresistances of these oxides are revealed to decrease at high pressure above 1 GPa. Extremely large Grüneisen parameters are found near x = 0.2, where the metal-insulator transition occurs. The origin for these properties will be briefly discussed in connection with the phase diagram.

scholarly journals Metallic state and the metal-insulator transition ofNdNiO3

1993 ◽  
Vol 48 (16) ◽  
pp. 11666-11672 ◽  
Author(s):  
X. Granados ◽  
J. Fontcuberta ◽  
X. Obradors ◽  
Ll. Mañosa ◽  
J. B. Torrance
Keyword(s):  
Insulator Transition ◽  
Metallic State ◽  
Metal Insulator Transition ◽  
Metal Insulator

Exploiting the Metal-Insulator Transition of VO2 Thin Films for Terahertz Wave Modulation and Switching

2015 ◽  
Vol 1805 ◽  
Author(s):  
Md Nadim Ferdous Hoque ◽  
Gulten Karaoglan-Bebek ◽  
Mark Holtz ◽  
Ayrton A. Bernussi ◽  
Zhaoyang Fan
Keyword(s):  
Thin Films ◽  
Charge Density ◽  
Amplitude Modulation ◽  
Modulation Depth ◽  
Insulator Transition ◽  
Thz Radiation ◽  
Metallic State ◽  
Light Modulator ◽  
Metal Insulator Transition ◽  
Metal Insulator

ABSTRACTVO2 is one of the very few natural materials that can be used to modulate terahertz (THz) radiations. A 100-nm thick VO2, when in its metallic phase, has a charge density of more than ∼ 1015 cm-2 which will strongly reflect and absorb the THz radiation; while in its insulator state, the charge density is lowered by several orders of magnitude to be THz transparent. Therefore, exploiting the metal-insulator transition of VO2 is a potential approach to modulate or even switch THz radiation for THz optics. Here we report that VO2 epitaxial thin films on sapphire substrate exhibits 85% amplitude modulation depth in a broad bandwidth, while this value can be improved to 95% when VO2 film is coated on both sides of a substrate. We further demonstrate that with wafer bonding, 4-layered VO2 thin films exhibit a transmittance as low as -20 dB to -30 dB at their metallic state, enough for switching applications. We also report our proof-of-concept demonstration of THz spatial light modulator that exhibits amplitude modulation as large as 96%, -30 dB pixel-to-pixel crosstalk, and a broad THz bandwidth.

scholarly journals Metal–Insulator Transition in Three-Dimensional Semiconductors

Symmetry ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1345
Author(s):  
Klaus Ziegler
Keyword(s):  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Critical Point ◽  
Order Parameter ◽  
Three Dimensional ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Metallic Behavior ◽  
Metal Insulator ◽  
Scattering Rate

We use a random gap model to describe a metal–insulator transition in three-dimensional semiconductors due to doping, and find a conventional phase transition, where the effective scattering rate is the order parameter. Spontaneous symmetry breaking results in metallic behavior, whereas the insulating regime is characterized by the absence of spontaneous symmetry breaking. The transition is continuous for the average conductivity with critical exponent equal to 1. Away from the critical point, the exponent is roughly 0.6, which may explain experimental observations of a crossover of the exponent from 1 to 0.5 by going away from the critical point.

Metastable metallic state and hysteresis below the metal-insulator transition inPrNiO3

1992 ◽  
Vol 46 (24) ◽  
pp. 15683-15688 ◽  
Author(s):  
X. Granados ◽  
J. Fontcuberta ◽  
X. Obradors ◽  
J. B. Torrance
Keyword(s):  
Insulator Transition ◽  
Metallic State ◽  
Metal Insulator Transition ◽  
Metal Insulator

scholarly journals A local metallic state in globally insulating La1.24Sr1.76Mn2O7 well above the metal–insulator transition

2007 ◽  
Vol 3 (4) ◽  
pp. 248-252 ◽  
Author(s):  
Z. Sun ◽  
J. F. Douglas ◽  
A. V. Fedorov ◽  
Y.-D. Chuang ◽  
H. Zheng ◽  
...  
Keyword(s):  
Insulator Transition ◽  
Metallic State ◽  
Metal Insulator Transition ◽  
Metal Insulator
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