[12p-A501-1~16] 10.4 Semiconductor spintronics, superconductor, multiferroics

[12p-A501-16] How Should We Derive the Noise Spectrum from Multiple Spin-Echo Decays?

〇Susumu Sasaki^1,2, Takanori Miura³, Kosuke Ikeda³, Masahiro Sakai³, Takuya Sekikawa³, Masaki Saito³, Tatsuro Yuge⁴, Yoshiro Hirayama^4,5 (1.Niigata Univ, Eng., 2.AMED, 3.Niigata Univ, Grad, 4.Shizuoka Univ, Sci., 5.Tohoku Univ, Sci)

Keywords:coherence, noise spectrum, GaAs

It is well known that, in addition to enhancing the coherence time, applying multiple π-pulses works to obtain the decoherence noise spectra. In these studies, however, some report the usual 1/fnoise, but others 1/f³spectra, resulting in a controversial situation. Moreover, very little has been discussed on how to deduce the spectral intensities from their raw data: the multiple-echo decay. In this paper, we show that two theories solve these issues and that the method is free from experimental artifacts. As a result, we found that, for ⁷⁵As nuclear spins in GaAs, the noise spectrum exhibits neither the usual 1/f noise nor the 1/f³with no physical pictures, but a Loerntzian 1/f²spectrum at 297 K. This indicates that the noise is ascribed to the fluctuation of dipole moment of the nearest neighboring As nuclear spins.