Thermoelectricity turns a corner

The Peltier effect is a popular means by which an electrical current can be used for heating or cooling in technological applications. Harnessing this effect typically requires a junction between two different conducting materials with different Peltier coefficients—a measure of how much heat is carried by the current. Ken-ichi Uchida and colleagues now report the observation of a Peltier-like effect in a single material (nickel) without junctions. Key to this is the realization that, in some magnetic materials, the Peltier coefficient will depend on the orientation of the charge current relative to the magnetization direction. If the current can be made to change direction in the material, as simple as going round a corner, then the Peltier coefficient also changes and the net effect is equivalent to that of a conventional junction-based Peltier heat pump. The material simplicity of this approach might prove useful for the development of chip-scale thermal management systems.