Cyclotron Spin-Flip Excitations in a v = 1/3 Quantum Hall Ferromagnet

摘要

Inelastic light scattering spectroscopy discloses a novel type of cyclotron spin-flip excitation in a quantum Hall system around the v = 1/3 filling. The excitation energy follows qualitatively the degree of electron spin polarization, reaching a maximum value at v = 1 /3. This characterizes the new excitation as a v = 1/3 ferromagnet eigenmode. The mode energy exceeds drastically the theoretical prediction obtained within the renowned single-mode approximation. We develop a new theoretical approach where the basis set is extended by adding a double-exciton component representing the cyclotron magneto-plasmon and spin wave coupled together. This double-mode approximation, inferred to be responsible for substantially reducing the gap between theoretical and experimental results, shows that the cyclotron spin-flip excitation is effectively a four-particle state.