Probing ultrahigh magneto-optical properties and time-resolved spin dynamics in InAsP ternary alloys

InAsP ternary alloys are not only important for potential spintronics applications owing to their tunability of their g-factors but also for high speed electronic and optoelectronic devices due to their variable band gap of 0.35-1.35 eV. We present a room temperature cyclotron resonance (CR) study of n-type InAs_xP_1−x (x=0.07,0.34) films in ultrahigh magnetic fields in the Faraday’s geometry. Our results are compared to theoretical calculations based on the k.p method with a modified 8-band Pidgeon-Brown model with good agreement. A near-zero g-factor is suggested by the theoretical Landau-level fan diagram for x=0.34, and the absorption coefficients show excellent agreement with the CR measurements. As an important extension, we investigate light-induced spin dynamics in the non-magnetic InAs_0.34P_0.66 employing ultrafast degenerate time resolved Magneto-optic Kerr Effect (MOKE) using the Voigt geometry. At the pump/probe energy of 960 nm at 300 K, our polarization-resolved B=0 data show helicity-dependent spin relaxation times. Moreover for the right-circularly polarized pump, we have probed a B-dependent relaxation time and precession frequency.