EAGER: A Novel Class of Magnetic Materials with Anisotropic Curie Temperature
Chopra, Harsh Principal Investigator
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NON-TECHNICAL All known crystals of magnetic materials possess magnetism regardless of the crystal direction in which measurements are made. Moreover, the magnetic properties disappear when the crystal is heated above a certain temperature, called the Curie temperature. This EAGER project seeks to establish the existence of an exciting and entirely new class of magnetic materials that are magnetic in a given crystal direction while being non-magnetic along other directions. While the existence of such materials has been conjectured ever since the beginnings of the development of the modern theory of magnetism in the late 19th and the 20th centuries, the proof of their existence has remained elusive. Experimental proof requires unconventional and ultra-sensitive instrumentation, employing a nanofabricated device to measure such small quantities of heat exchange simultaneously with electrical properties of the sample. While a high-risk project, positive results obtained from it would be transformative and yield high payoff in spurring efforts to discover similar materials and expanding current theoretical understanding of the physics of magnetism. Since the Curie temperature is a fundamental material property, all effects dependent on it would also exhibit unusual behavior, potentially leading to a gamut of new magnetic sensors and actuators. The project would provide opportunities for a post-doctoral fellow to work, and mentor two undergraduate students, on experiments related to microfabrication, magnetism, calorimetry, and electrical properties, which have broad relevance to academia and industry. TECHNICAL This EAGER project seeks to establish the existence of an entirely new class of magnetic materials that have anisotropic Curie temperature. Such materials would have the unique property, at a specific temperature, of being ferrimagnetic along a given crystal direction while being paramagnetic along other directions. While their existence has long been conjectured and theorized, the project identifies key materials characteristics necessary for the manifestation of such unusual magnetic behavior. A novel set of experiments was specifically designed to demonstrate the effect in a material that exhibits a distinct dependence of its magnetic susceptibility on crystal orientation. The successful outcome of this high-risk project would be transformative and yield a high payoff from both fundamental as well as technological viewpoints, spurring experimental efforts to discover similar materials as well as enabling the expansion of the current theoretical framework of the physics of magnetism. Since the Curie temperature of a material is an intrinsic property, all effects dependent on it would also exhibit unusual directional behavior, leading to a gamut of new magnetic sensors and actuators. The project will provide opportunities for a post-doctoral fellow to pursue a tenure track faculty position and to mentor two undergraduate students, working on experiments related to microfabrication, magnetism, pJ calorimetry, and electron transport, which have broad relevance for academia and industry.