We report on an observation of a fractional quantum Hall effect in an ultrahigh-quality two-dimensional hole gas hosted in a strained Ge quantum well. The Hall resistance reveals precisely quantized plateaus and vanishing longitudinal resistance at filling factors ν = 2/3,4/3, and 5/3. From the temperature dependence around ν = 3/2 we obtain the composite fermion mass of m_ ≈ 0.4me, where me is the mass of a free electron. Owing to large Zeeman energy, all observed states are spin polarized and can be described in terms of spinless composite fermions.

• Publication: PHYSICAL REVIEW B 91, 241303(R) (2015)
• DOI: 10.1103/PhysRevB.91.241303