51 citations · 357 across the 32 of their papers we have counts for
32 papers
Observation of the orbital Nernst effect
Yuto Masuda, Takamasa Hirai, Daegeun Jo +5
The Nernst effect, which converts a temperature gradient into a transverse charge current, is fundamental to thermoelectrics. Its spin analogue, the spin Nernst effect, enables the…
Observation of the Nernst effect driven by longitudinal spin fluctuations
Fuyuki Ando, Hiroto Adachi, Hossein Sepehri-Amin +3
The Nernst effect, which converts a heat current into a charge current in the orthogonal direction, is generally classified into the ordinary effect due to an external magnetic fie…
Observation of nonlocal ferron-drag thermoelectricity
Takuma Itoh, Takamasa Hirai, Ping Tang +8
The Peltier effect induces a heat current when a charge current passes through a conductor. Since a charge current is conserved at the junction between two different conductors, th…
Realizing record-high transverse thermoelectric figure of merit at room temperature in artificially tilted multilayers based on high power factor NiFe alloy
Yebin Lee, Fuyuki Ando, Takamasa Hirai +3
Transverse thermoelectric conversion using artificially tilted multilayers (ATMLs) offers a versatile device architecture that circumvents the structural limitations of conventiona…
Observation of giant nonvolatile magneto-thermal switching in superconductor-ferromagnet hybrids
Yui Sakamoto, Fuyuki Ando, Keigo Ito +6
Magneto-thermal switch is a crucial thermal component which enables heat transfer control by the application of an external magnetic field. Recently, a nonvolatile behavior in magn…
Revealing nonvolatile behaviors in magneto-thermal switching using microstructure-controlled superconducting composites
Keigo Ito, Yui Sakamoto, Hossein Sepehri-Amin +12
Thermal conductivity in a conductor changes by the application of an external magnetic field, which functions as a magneto-thermal switch. For superconductors, a large magneto-ther…
Observation of orbital-angular-momentum-driven temperature modulation via the spin Peltier effect
Sang J. Park, Tsuneyoshi Kan, Takamasa Hirai +1
Angular-momentum transport provides a pathway for controlling energy flow in solids beyond conventional charge-based mechanisms. While spin currents are known to mediate spin-calor…
Spin caloritronics: History and future prospects of experiments
Ken-ichi Uchida, Takamasa Hirai
Since the beginning of the 21st century, novel energy conversion and control principles utilizing the spin degree of freedom have been discovered in the field of spin caloritronics…
Trans-scale spin Seebeck effect in nanostructured bulk composites based on magnetic insulator
Sang J. Park, Keisuke Hirata, Hossein Sepehri-Amin +3
The spin Seebeck effect (SSE) enables thermoelectric conversion through thermally generated spin currents in magnetic materials, offering a promising transverse geometry for scalab…
High-throughput development of flexible amorphous materials showing large anomalous Nernst effect via automatic annealing and thermoelectric imaging
Sang J. Park, Ravi Gautam, Abdulkareem Alasli +5
This work demonstrates high-throughput screening of flexible magnetic materials for efficient transverse thermoelectric conversion based on the anomalous Nernst effect (ANE). The a…
Fundamentals and advances in transverse thermoelectrics
Hiroto Adachi, Fuyuki Ando, Takamasa Hirai +3
Transverse thermoelectric effects interconvert charge and heat currents in orthogonal directions due to the breaking of either time-reversal symmetry or structural symmetry, enabli…
Study of magneto-thermal resistance effect in a Co50Fe50/Cu multilayer through the analysis of electron and lattice thermal conductivities
Fuya Makino, Takamasa Hirai, Takuma Shiga +8
This study investigates the giant magneto-thermal resistance (GMTR) effect in a fully-bcc epitaxial Co50Fe50/Cu multilayer through both experimental and theoretical approaches. The…
Quantitative measurements of transverse thermoelectric generation and cooling performances in SmCo/BiSbTe-based artificially tilted multilayer module
Masayuki Murata, Fuyuki Ando, Takamasa Hirai +2
The transverse thermoelectric generation and cooling performances in a thermopile module composed of recently developed SmCo/BiSbTe artificially tilted mult…
Quantitative noncontact measurement of thermal Hall angle and transverse thermal conductivity by lock-in thermography
Takumi Imamura, Takamasa Hirai, Koichi Oyanagi +4
We propose and demonstrate a quantitative noncontact measurement method for the thermal Hall effect (THE) based on magnetic-field-modulated lock-in thermography. This method enable…
Adiabatic transverse thermoelectric conversion enhanced by heat current manipulation in artificially tilted multilayers
Fuyuki Ando, Takamasa Hirai, Hiroto Adachi +1
We phenomenologically formulate and experimentally observe an adiabatic transverse thermoelectric conversion enhanced by a heat current re-orientation in artificially tilted multil…
Simultaneous achievement of large anomalous Nernst effect and reduced thermal conductivity in sintered polycrystalline topological Heusler ferromagnets
Koichi Oyanagi, Hossein Sepehri-Amin, Kenta Takamori +9
This study reports the observation of the large anomalous Nernst effect in polycrystalline ferromagnetic CoMnGa (CMG) slabs prepared by a spark plasma sintering method. By op…
Observation of transverse Thomson effect
Atsushi Takahagi, Takamasa Hirai, Abdulkareem Alasli +3
The thermoelectric Thomson effect, predicted in the 1850s by William Thomson, produces volumetric heating/cooling in a conductor due to the concerted action of the Seebeck and Pelt…
Designing flexible hard magnetic materials for zero-magnetic-field operation of the anomalous Nernst effect
Sang J. Park, Rajkumar Modak, Ravi Gautam +6
The global shift towards a carbon-neutral society has accelerated the demand for green energy, driving research into efficient technologies for harvesting energy from low-grade was…
Hybridizing anomalous Nernst effect in artificially tilted multilayer based on magnetic topological material
Takamasa Hirai, Fuyuki Ando, Hossein Sepehri-Amin +1
Transverse thermoelectric conversion holds significant potential in addressing complex challenges faced by classical Seebeck/Peltier modules. A promising transverse thermoelectric…
Non-equilibrium Magnon Engineering Enabling Significant Thermal Transport Modulation
Takamasa Hirai, Toshiaki Morita, Subrata Biswas +13
Thermal conductivity, a fundamental parameter characterizing thermal transport in solids, is typically determined by electron and phonon transport. Although other transport propert…
Multifunctional composite magnet realizing record-high transverse thermoelectric generation
Fuyuki Ando, Takamasa Hirai, Abdulkareem Alasli +4
Permanent magnets are used in various products and essential for human society. If omnipresent permanent magnets could directly convert heat into electricity, they would lead to in…
Quantitative measurement of figure of merit for transverse thermoelectric conversion in Fe/Pt metallic multilayers
Takumi Yamazaki, Takamasa Hirai, Takashi Yagi +4
This study presents a measurement method for determining the figure of merit for transverse thermoelectric conversion () in thin film forms. Leveraging the propose…
Creation of flexible spin-caloritronic material with giant transverse thermoelectric conversion by nanostructure engineering
Ravi Gautam, Takamasa Hirai, Abdulkareem Alasli +4
Functional materials such as magnetic, thermoelectric, and battery materials have been revolutionized through nanostructure engineering. However, spin caloritronics, an advancing f…
Permanent-magnet-based transverse thermoelectric generator with high fill factor driven by anomalous Nernst effect
Fuyuki Ando, Takamasa Hirai, Ken-ichi Uchida
A transverse thermoelectric generator for magnetic-field-free and high-density power generation utilizing the anomalous Nernst effect is constructed and its performance is characte…