An NSF Materials Research Science and Engineering Center (MRSEC)

1. Center for Emergent Materials The Ohio State University http://cem.osu.edu Giant spin-Seebeck effect could provide power from waste heat spin/phonon effect increased 1000-fold in semiconductor with strong spin-orbit interactions An OSU research team has been studying the interaction between heat and magnetic materials. One such effect, called the spin-Seebeck effect, allows for heat to move magnetic information. The magnetic information is then converted into electrical power. The OSU team previously observed the effect to occur in a magnetic semiconductor but it produced small electrical power. The effect can be maximized when heat particles, called phonons, drag the magnetic moments. This past year, the OSU team discovered that the effect is 1000 times larger in a material that contains no magnetism. This strange result is explained since the electrical charges in the material can also have magnetism due to a property called spin. The effect is strong enough that the OSU team is now examining if it might be useful for converting heat into electrical power based on this spin effect. Their research is now focused on determining what properties allow heat/magnetism/spin effects to become largest and then producing materials that display those effects. (left) When heat causes atoms to vibrate in a crystal, those vibrations can rotate the magnetism of electrical charges, called spin. (right) The spin is then converted into electrical power using a metal strip. Co Au Co Roberto Myers (Materials Science Engineering), Chris Jaworski, Joseph Heremans (Mechanical Engineering), and Ezekiel Johnston-Halperin (Physics) An NSF Materials Research Science and Engineering Center (MRSEC) Supported under Award Number DMR-0820414