Very large magnetoresistance in electrodeposited single-crystal Bi thin films (invited)

Abstract

Single-crystal bismuth thin films, fabricated by electrodeposition and suitable annealing, exhibit very large magnetoresistance of 400 000% at 5 K and 300% at 300 K, as well as pronounced Shubnikov-de Haas oscillations. A hybrid structure demonstrates the potential for field sensing with sensitivities of 35%/Oe at 5 K and 0.2%/Oe at 300 K.

I–V characteristic and magnetoresistance of homogeneous materials

“…Before carrying out the evaluation of A 0 , we remark that the expression (3.5) for the current is independent of the direction of the applied magnetic field, and depends only on its magnitude. This is in accord with experimental findings, indirectly, through MR measurements, e.g., [4,5], whereby the MR is independent of the sign of the magnetic field. However, reversing the direction of the magnetic field causes reversal in the Hall polarity.…”

Effect of spin-orbit coupling on magnetoresistance in organic semiconductors

“…6 In addition to its potential applications, OMAR poses a significant scientific puzzle since it is, to the best of our knowledge, the only known example of large room-temperature magnetoresistance in nonmagnetic materials with the exception of high-mobility materials. 7,8 To the best of our knowledge the mechanism causing OMAR is currently not known with certainty, although two theories based on spin dynamics have been suggested very recently. 6,9 In general, magnetoresistance in nonmagnetic devices can be caused by several different physical principles: ͑i͒ Lorentz force deflection, causing effects like Hall voltages, classical magnetoresistance, and extraordinary magnetoresistance, 10 ͑ii͒ quantum-mechanical diamagnetism, such as effects associated with Landau levels or hopping magnetoresistance, 11 ͑iii͒ interference phenomena such as weak localization 12 that are sensitive to magnetic fields because the vector potential enters the Schrödinger equation in a way that leads to phase shifts, and finally ͑iv͒ spin dynamics.…”

Magnetoconductivity and magnetoluminescence studies in bipolar and almost hole-only sandwich devices made from films of a π-conjugated molecule

“…Other laboratories have also observed this effect [16][17][18][19][20][21]. OMAR poses a significant scientific puzzle since it is, to the best of our knowledge, the only known example of large room temperature magnetoresistance in non-magnetic materials with the exception of very-high-mobility materials [22,23]. Moreover, the discovery of OMAR begs the question why a corresponding effect has not yet been discovered in inorganic semiconductors, whereas it appears to be ubiquitous in organic semiconductors [6].…”