Observation of fractional quantum Hall effect in an InAs quantum well

The two-dimensional electron system in an InAs quantum well has emerged as a prime candidate for hosting exotic quasi-particles with non-Abelian statistics such as Majorana fermions and parafermions. To attain its full promise, however, the electron system has to be clean enough to exhibit electron-electron interaction phenomena. Here we report the observation of fractional quantum Hall effect in a very low disorder InAs quantum well with a well-width of 24 nm, containing a two-dimensional electron system with a density $n=7.8\times {10}^{11}$ cm${}^{-2}$ and low-temperature mobility $1.8 \times 10^6$cm$^2$\mathrm{/}Vs\mathrm{.}Atatemperatureof$\simeq35$mKand$B\simeq24$ T, we observe a deep minimum in the longitudinal resistance, accompanied by a nearly quantized Hall plateau at Landau level filling factor $\nu =4\mathrm{/}3$.