Melting and resistivity of iron at Earth core conditions using pulsed Joule heating.

Microsecond pulsed Joule heating in diamond anvil cells shows iron’s melting curve is surprisingly shallow, reaching 6 K/GPa and 4160 ± 80 K at 200 GPa.

• Why it matters: Earth-core melting and electrical resistivity constrain models of core temperature, heat flow, and whether convection could sustain the geodynamo before inner-core growth.
• What they did: The team performed over 300 reproducible melting tests and measured liquid iron resistivity using a 76 cm setup, then extrapolated to pressure and alloy composition.
• The result: They infer a core-mantle boundary temperature of 3430 K and an adiabatic outer-core heat flow of 9.8 TW, implying convection may have powered the geodynamo and the lowermost mantle is fully solid.

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