Magnetically enhanced thermoelectrics: a comprehensive review

Abstract

Thermoelectric (TE) materials have great potential for waste-energyrecycling and solid-state cooling. Their conversion efficiency has attracted huge attention to the development of TE devices, and largely depends on the thermal and electrical transport properties. Magnetically enhanced thermoelectrics open up the possibility of making thermoelectricity a future leader in sustainable energy development and offer an intriguing platform for both fundamental physics and prospective applications. In this review, state-of-the-art TE materials are summarized from the magnetism point of view, via diagrams of the charges, lattices, orbits and spin degrees of freedom. Our fundamental knowledge of magnetically induced TE effects is discussed. The underlying thermo-electro-magnetic merits are discussed in terms of superparamagnetism-and magnetic-transition-enhanced electron scattering, field-dependent magnetoelectric coupling, and the magnon-and phonon-drag Seebeck effects. After these topics, we finally review several thermal-electronic and spin current-induced TE materials, highlight future possible strategies for further improving ZT, and also give a brief outline of ongoing research challenges and open questions in this nascent field.

Carrier grain boundary scattering in thermoelectric materials

“…6 After reaching the n opt , a further enhancement in TE performance could be realized either through engineering the intrinsic electronic and phonon structures [7][8][9] or modulating the carrier and phonon scattering mechanisms, [10][11][12] aiming at the higher electrical power factor (PF = S 2 s), and the lower k L . There have been some effective strategies developed in recent years through the modulation of electronic band degenceracy, [13][14][15][16][17] band curvature, [18][19][20][21] valley anisotropy, 22,23 phonon anharmonicity, [24][25][26][27] multiscale phonon scattering, [28][29][30][31][32][33] and magnetism, [34][35][36][37] to name just a few.…”

Recent progress in phosphide materials for thermoelectric conversion

“…72 Mn 2+ can be used instead of Zn 2+ due to localisation of the 3d 5 electrons, also yielding semiconducting materials with similar behaviour but a lower max zT, 73 but brings the prospect of coupling to magnetism. 101,102 The performance of YbCuZnP 2 -based compositions with 1 : 1 mixtures of Cu + and Zn 2+ (valence balanced through incorporation of Yb 3+ ) is much more promising. YbCuZnP 2 was found to have near constant r(T) ∼ 22 mU m (5 orders of magnitude smaller than CaZn 2 P 2 ) above 300 K and a high temperature S ∼ 160 mV K −1 at 970 K, leading to S 2 s 970 K ∼ 1.1 mW m −1 K −2 .…”

“…72 Mn 2+ can be used instead of Zn 2+ due to localisation of the 3d 5 electrons, also yielding semiconducting materials with similar behaviour but a lower max zT , 73 but brings the prospect of coupling to magnetism. 101,102…”

Structure, Magnetic and Thermoelectric Properties of High Entropy Selenides Bi0.6Sb0.6In0.4Cr0.4Se3

“…It is known that ferromagnetic materials have strong magnetism after being magnetized at low temperature. With increasing temperature, the magnetic domains and moment would be strongly affected by the intensification of lattice vibration [29] . When the temperature above the Curie temperature, the magnetic domain is collapsed and the average magnetic moment becomes zero, then the ferromagnetic substance changes into a paramagnetic substance.…”