Experimental observation of Fröhlich superconductivity in high magnetic fields

Resistivity and irreversible magnetisation data taken within the high magnetic field CDWx phase of the quasi-two-dimnesional organic metal α-(BEDT-TTF)2KHg(SCN)4 are shown to be consistent with a field-induced inhomogeneous superconducting phase. In-plane skin depth measurements show that the resistive transition on entering the CDWx phase is both isotropic and representative of the bulk. Prior to the development of the BCS theory of superconductivity [1], Fröhlich proposed a novel form of superconductivity in one-dimensional (1D) metals due to spontaneously sliding charge-density waves (CDWs). [2]. CDWs were subsequently discovered in many quasi-1D metals [3]; however, such systems are generally insulators, due to pinning of the CDW [3]. The organic conductor α-(BEDT-TTF)2KHg(SCN)4 (together with the analogue compounds in which K has been subtituted by Tl or Rb) may be an exception [4]. This highly anisotropic layered metal exhibits what is thought