Critical component of Earth’s magnetic field revealed

Iron’s presence in the Earth’s core cannot alone explain its magnetic field, according to researchers in Switzerland.

The scientists calculated that the Earth’s core contains up to 20% nickel. When subjected to large amounts of pressure, nickel behaves very differently than iron, and this is what scientists believe helps create the planet’s magnetic field.

Nickel’s unusual effect

Professor Alessandro Toschi, from the Vienna University of Technology, said: “At high pressure, the electrons in nickel tend to scatter much more than the electrons in iron. As a consequence, the thermal conductivity of nickel and, thus, the thermal conductivity of the earth's core is much lower than it would be in a core consisting only of iron.”

The Earth’s core is about the size of the Moon, as hot as the Sun’s surface, with a pressure range between 330 and 360 gigapascals. The high nickel proportion means that heat from the Earth’s core cannot flow towards the planet’s surface through electron movement alone. Convection currents are caused by high temperatures and coupled with the Earth’s rotation, combine to produce a spiralling flow of hot material.

To obtain these results, different metallic structures were analysed in large-scale computer simulations before the behaviour of their electrons was calculated. Iron and nickel were analysed as well as alloys of the two materials. These advanced calculations, in addition to better understanding the Earth’s magnetic field, have provided new insights into how electrons scatter in different materials.

Professor Toschi said: “When electrical currents are created in such a system of flows, they can cause a magnetic field which in turn increases the electrical current and so forth – and finally the magnetic field becomes so strong that we can measure it on the surface of the earth.”

The research was carried out alongside scientists from Würzburg University in Germany. The research was published in Nature Communications.