Large Electric Field Effect in Electrolyte-Gated Manganites

Abstract

We have studied electrostatic field-induced doping in La0.8Ca0.2MnO3 transistors using electrolyte as a gate dielectric. For positive gate bias, electron doping drives a transition from a ferromagnetic metal to an insulating ground state. The thickness of the electrostatically doped layer depends on bias voltage but can extend to 5 nm requiring a field doping of 2x10;{15} charges per cm;{2} equivalent to 2.5 electrons per unit cell area. In contrast, negative gate voltages enhance the metallic conductivity by 30%.

Hopping transport and the Hall effect near the insulator–metal transition in electrochemically gated poly(3-hexylthiophene) transistors

“…In essence, the device is a four-terminal bottom-contacted van der Pauw geometry P3HT thin film transistor, gated electrochemically using an ion gel based on an ionic liquid (1-ethyl-3-methylimidazolium bis(trifluoro-methylsulfonyl) imide ((EMIM)(TFSI))) and a triblock copolymer (poly(styrene-b-methylmethacrylate-b-styrene; PS-PMMA-PS)) [19][20][21] . Such ionic liquids and gels have been used recently to electrostatically induce two-dimensional charge densities B10 14 cm À 2 in a variety of materials (for example, refs [22][23][24][25]. In the case of semi-crystalline semiconducting polymers such as P3HT, the open structure results in deep penetration of the dopant ions, providing uniform 3D electrochemical doping (Fig.…”

Electrical Manipulation of Orbital Occupancy and Magnetic Anisotropy in Manganites

“…[14,15] However, the lattice distortion inevitably introduces impurities and extra 3 scattering centers to the system, which are irreversible and hardly controllable, and the orbital occupancy is fixed once the materials have been made and put into use. Application of the field-effect transistor principle to achieve doping variation has modulated the magnetic or electric performances and phase transition in manganites, [16,17] which is expected to provide an approach to tuning orbital occupancy reversibly. The main technological challenge for measuring the change of the orbital order under the influence of an electric field is that the detection of orbital occupancy using x-ray linear dichroism (XLD), calls for an exposed sample with a robust remanent electric field effect, [18] which cannot be achieved by conventionally electrostatic modification of carrier density.…”

Tunable topological states in electron-doped HTT-Pt

“…In conventional solid-state field-effect transistors, 5 the electron doping concentration can reach ~10 12 cm -2 , at which the electrons behave as chiral particles accompanied by unexpected physical phenolmena. 6,7 Using a solid polymer electrolyte gate with higher capacitance, 8 the electron doping concentration in bilayer graphene can be up to 5×10 13 cm -2 , resulting in a significant band gap and breaking of inversion symmetry. 9,10 In recent experiments, the doping level for both electrons and holes was increased to ~10 14 cm -2 by employing high-capacitance gate insulator, 11 such as Li salt (LiClO 4 or Li bis(trifluoromethylsulfonyl)imide (LiTFSI)) dissolved inpoly (ethylene oxide) (PEO), 12 which can be used to modulate magnetoresistance 13 and induce superconductivity at the surface of insulators.…”