Abstract
Peltier effects, which produce a heat flux at the junction of two different materials, have been an important technology for heating and cooling by electrical means. Whereas Peltier devices have advantages such as cleanliness, silence, compactness, flexibility, reliability, and efficiency, relatively complicated modular structures are unavoidable, leading to a higher cost than that of commonly used refrigeration technology. Here, we provide a concept of a Peltier device composed of a single magnetic material exhibiting a first-order magnetic transition. Our concept is based on a controllable junction structure consisting of two magnetic phases with opposite Peltier coefficients instead of a semiconductor junction. Using {mathrm{Mn}}_{1.96}{mathrm{Cr}}_{0.04}mathrm{Sb} samples with the first-order magnetic transition between ferrimagnetic (FI) and antiferromagnetic (AF) states, we successfully made a stable junction structure of AF/FI/AF by a pulse heating method and achieved a maximum Peltier coefficient of 0.58 mV. Our device concept was further verified by a numerical simulation based on a finite element method. The single-material Peltier effect reported here avoids a complex device design involving material junctions and is importantly reconfigurable.
Highlights
Combining the effects of magnetism, heat, phase change and other effects at the material level can produce diversified functions, which is of great significance for achieving high integration of devices[1,2,3]
A heat current is generated by a pure spin current, which is the reciprocal effect of the spin Seebeck effect, namely, the spin Peltier effect[9,10]. Another example is Peltier cooling and heating by using the anisotropic magneto-Peltier effect[11], which offers a single-material Peltier device as opposed to the conventional Peltier devices based on a material junction; generally, Peltier cooling and heating devices consist of a junction of two conductors with different Peltier coefficients ( ΠA and ΠB )
The heat density absorbed at the interface per unit time Qis proportional to the difference between the two Peltier coefficients as follows: Q = (ΠA − ΠB)J = ΠA/BJ, where ΠA/B is the Peltier coefficient of the junction structure
Summary
Combining the effects of magnetism, heat, phase change and other effects at the material level can produce diversified functions, which is of great significance for achieving high integration of devices[1,2,3]. Since the metastable state can be created, annihilated, and driven by local heating[18,19], magneto-optical effects[20,21], and spin transfer/orbit torque[22,23], the single-material Peltier device proposed here is highly reconfigurable and controllable, which is difficult to realize in conventional Peltier devices based on p-n junctions and a single-material Peltier device utilizing anisotropic magneto-Peltier e ffect[8] To demonstrate this concept, we use the Mn2−xCrx Sb compound, which shows an abrupt change in the Seebeck coefficient at a first-order transition temperature[16,17]. Note that for the compounds with a very small chromium
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