Direct Measurement of Sheet Resistance R□ in Cuprate Systems: Evidence of a Fermionic Scenario in a Metal-Insulator Transition

P. Orgiani; C. Aruta; G. Balestrino; D. Born; L. Maritato; P. G. Medaglia; D. Stornaiuolo; F. Tafuri; A. Tebano

doi:10.1103/PhysRevLett.98.036401

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Direct Measurement of Sheet Resistance R□ in Cuprate Systems: Evidence of a Fermionic Scenario in a Metal-Insulator Transition

P. Orgiani, C. Aruta, G. Balestrino, D. Born, L. Maritato, P. G. Medaglia, D. Stornaiuolo, F. Tafuri, A. Tebano

DOI 10.1103/PhysRevLett.98.036401 · Physical Review Letters

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Abstract

The metal-insulator transition (MIT) has been studied in Ba0.9Nd0.1CuO2+x/CaCuO2 ultrathin cuprate structures. Such structures allow for the direct measurement of the 2D sheet resistance R□, eliminating ambiguity in the definition of the effective thickness of the conducting layer in high temperature superconductors. The MIT occurs at room temperature for experimental values of R□ close to the 25.8 kΩ universal quantum resistance. All data confirm the assumption that each CaCuO2 layer forms a 2D superconducting sheet within the superconducting block, which can be described as weak-coupled equivalent sheets in parallel.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
(BaCuO2+x)m/(CaCuO2)n Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	80	Pressure not reported	zero_resistance
Ba0.9Nd0.1CuO2+x/CaCuO2/Ba0.9Nd0.1CuO2+x Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	60	Pressure not reported	unknown