Magnetotunneling as a Probe of Luttinger-Liquid Behavior

A novel method for detecting Luttinger-liquid behavior is proposed. The idea is to measure the tunneling conductance between a quantum wire and a parallel two-dimensional electron system as a function of both the potential difference between them, $V$, and an in-plane magnetic field, $B$. We show that the two-parameter dependence on $B$ and $V$ allows for a determination of the characteristic dependence on wave vector $q$ and frequency $\omega$ of the spectral function, $A_{\mathrm{LL}}(q,\omega )$, of the quantum wire. In particular, the separation of spin and charge in the Luttinger liquid should manifest itself as singularities in the $I$- $V$ characteristics. The experimental feasibility of the proposal is discussed.