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The 0.7 (2e^2/h) conductance anomaly is studied in strongly confined, etchedGaAs/GaAlAs quantum point contacts, by measuring the differential conductanceas a function of source-drain and gate bias as well as a function oftemperature. We investigate in detail how, for a given gate voltage, thedifferential conductance depends on the finite bias voltage and find aso-called self-gating effect, which we correct for. The 0.7 anomaly at zerobias is found to evolve smoothly into a conductance plateau at 0.85 (2e^2/h) atfinite bias. Varying the gate voltage the transition between the 1.0 and the0.85 (2e^2/h) plateaus occurs for definite bias voltages, which defines a gatevoltage dependent energy difference $\Delta$. This energy difference iscompared with the activation temperature T_a extracted from the experimentallyobserved activated behavior of the 0.7 anomaly at low bias. We find \Delta =k_B T_a which lends support to the idea that the conductance anomaly is due totransmission through two conduction channels, of which the one with its subbandedge \Delta below the chemical potential becomes thermally depopulated as thetemperature is increased.Comment: 9 pages (RevTex) with 9 figures (some in low resolution

Bias and temperature dependence of the 0.7 conductance anomaly in quantum point contacts