Nonlinear electric field effects at a continuous mott-hubbard transition

Area of Science:

• Condensed Matter Physics
• Materials Science

Background:

• Highly correlated transition metal chalcogenides like Ni(S,Se)2 exhibit complex electronic behaviors.
• Understanding non-Ohmic conductivity at low temperatures is crucial for characterizing exotic electronic states.

Purpose of the Study:

• To investigate the non-Ohmic conductivity of Ni(S,Se)2 at temperatures below 1 Kelvin.
• To probe the influence of a quantum critical point on conductivity through pressure tuning.
• To determine the dynamical critical exponent (z) and analyze the spatial correlation length exponent (nu) and conductivity exponent (μ).

Main Methods:

• Experimental characterization of electrical conductivity in Ni(S,Se)2 at T < 1 K.
• Application of hydrostatic pressure to tune the metal-insulator transition at T = 0 K.
• Analysis using finite temperature scaling to extract critical exponents.

Main Results:

• The non-Ohmic conductivity was successfully characterized at low temperatures.
• Pressure tuning provided direct access to the quantum critical point.
• The dynamical critical exponent was determined to be z = 2.7(+0.3)(-0.4).
• Finite temperature scaling revealed that the spatial correlation length exponent (nu) and the conductivity exponent (μ) are distinct.

Conclusions:

• The study provides a detailed characterization of the non-Ohmic conductivity in Ni(S,Se)2.
• The findings highlight the significant role of the quantum critical point in this material's electronic properties.
• The determined critical exponents offer insights into the universality and scaling behavior near the metal-insulator transition.