INFLUENCE OF GAUGE-FIELD FLUCTUATIONS ON COMPOSITE FERMIONS NEAR THE HALF-FILLED STATE

Taking into account the transverse gauge-field fluctuations, which interact with composite fermions, we examine the finite-temperature compressibility of the fermions as a function of an effective magnetic field ΔB=B-2nehc/e (ne is the density of electrons) near the half-filled state. It is shown that, after including the lowest-order gauge-field correction, the compressibility becomes n/μec-Δω/2T[1 +[A(η)/(η-1)](Δωc)2/ (1+η)/T] for TΔωc, where Δωc=eΔB/mc. Here we assume that the interaction between the fermions is given by v(q)=V0/q2-η (1≤η≤2), where A(η) is an η-dependent constant. This result can be interpreted as a divergent correction to the activation energy gap and is consistent with the divergent renormalization of the effective mass of the composite fermions. © 1995 The American Physical Society.