Ultrafast demagnetization of ferromagnetic semiconductor InMnAs by dual terahertz and infrared excitations

Suhpicosecond pumping of ferromagnetic semiconductor InMnAs in the ranges of intra- and interband electronic transitions can result in an efficient demagnetization of the medium up to 60% of the initial magnetic moment. Here, we report about the efficiency of ultrafast demagnetization by a duo of terahertz and infrared pulses that trigger intra- and interband electronic transitions, respectively. Varying the intensities of the pulses and the delay between them, we study the degree of demagnetization caused by the pulse duo. It is shown that the result of the excitation does not depend on the pulse sequence. Our findings indicate that both intra- and interband electronic transitions result in ultrafast demagnetization of the semiconductor via the very same mechanism, which evolves at a ps timescale. Independent of the origin of the electronic transition, ultrafast demagnetization is a result of a temperature increase in the free charge carriers (holes). Published under license by AIP Publishing.