Abstract
The effect of phonon focusing on electron–phonon drag and thermopower in nanostructures based on potassium single crystals at low temperatures is studied. The role of quasi-longitudinal and quasi-transverse phonons, as well as shear waves, in the drag thermopower of the nanostructures is considered. It is shown that, in the Knudsen flow regime of a phonon gas, the slow quasi-transverse t2 mode makes the dominant contribution to the drag thermopower of the nanostructures and, only in directions close to the focusing of longitudinal phonons (L-phonons), their contribution become comparable to the contribution of the t2 mode. The directions of heat flux in which the maximum and minimum values of drag thermopower are achieved in nanowires, films, and nanoplates based on potassium single crystals are determined. The study of the effect of focusing on the phonon propagation in potassium single crystals made it possible to calculate a number of new, unusual effects in the anisotropy of drag thermopower in potassium-based nanostructures. These effects are mainly due to the competition between the contributions of the t2 mode and L-phonons to the drag thermopower. Since the relaxation rate of L-phonons on electrons in potassium is 25 times higher than for the t2 mode, with an increase in the transverse dimensions of potassium nanostructures, the anisotropy of the drag thermopower in them, in contrast to the anisotropy of thermal conductivity in dielectric nanostructures, changes nonmonotonically. It first increases, reaching a maximum, then decreases, and vanishes when the dimensions become macroscopic (D ≥ 10–1 cm). One of the interesting effects calculated in this work is the orientational anisotropy of drag thermopower in potassium nanoplates. In two identical nanoplates with a rectangular cross section, the thermopower in the direction of the temperature gradient [011] for the orientation of the wide faces of the {100} plates turns out to be significantly greater than for the {110} orientation. With increasing plate width, the orientational anisotropy of thermopower increases to 37%. It is shown that the orientational anisotropy of the thermopower is due to the effect of focusing on the phonon propagation in the plates. The competition between the contributions of the t2 mode and L-phonons, which determine the maximum and minimum values, leads to a nonmonotonic dependence of the orientational anisotropy of the drag thermopower on the thickness of the nanoplate. It is shown that, for square potassium films with {100} and {111} orientations of planes, the drag thermopower is isotropic in the film plane, but, for the {110} orientation, it becomes ellipsoidal with its major axis in the [001] direction. A characteristic feature of drag thermopower in square films is orientation anisotropy. For the [011] directions of the temperature gradient, the drag thermopower in potassium films with the {100} orientations of planes turns out to be significantly greater than with the {110} orientations. It behaves nonmonotonically, reaching a maximum of 57% at a thickness D = 2.2 × 10–5 cm. It is obvious that the effects calculated in this work open up new prospects for experimental studies of electron–phonon drag in metal films.
REFERENCES
I. I. Kuleyev and I. G. Kuleyev, “Effect of phonon focusing on the drag thermopower in single-crystal potassium nanowires at low temperatures,” Phys. Met. Metallogr. 122, 75–82 (2021). https://doi.org/10.1134/S0031918X21020071
I. G. Kuleyev and I. I. Kuleyev, “Effect of phonon focusing and shear waves on anisotropy of drag thermopower in potassium nanoplates,” Chin. J. Phys. 72, 351–359 (2021). https://doi.org/10.1016/j.cjph.2021.05.007
I. I. Kuleyev and I. G. Kuleyev, “Phonon focusing and anisotropy of drag thermopower in potassium thin films at low temperatures,” J. Phys. Chem. Solids 170, 110948 (2022). https://doi.org/10.1016/j.jpcs.2022.110948
I. I. Kuleev and I. G. Kuleev, “Dynamic properties and focusing of phonons in metallic and dielectric crystals of cubic symmetry. Review 1,” Phys. Met. Metallogr. 124 (2023).
I. I. Kuleyev and I. G. Kuleyev, “Phonon focusing and anisotropy of the lattice thermal conductivity of potassium crystals at low temperatures,” Phys. Met. Metallogr. 119, 1141–1147 (2018). https://doi.org/10.1134/S0031918X18120098
I. I. Kuleyev and I. G. Kuleyev, “Role of quasi-longitudinal and quasi-transverse phonons in the drage thermopower of potassium crystals at low temperatures,” J. Exp. Theor. Phys. 129, 46–58 (2019). https://doi.org/10.1134/S1063776119060141
I. G. Kuleyev and I. I. Kuleyev, “The effect of phonon focusing on the electron-phonon relaxation and electron transport in potassium crystals,” Chin. J. Phys. 68, 886–895 (2020). https://doi.org/10.1016/j.cjph.2020.10.005
I. I. Kuleyev and I. G. Kuleyev, “Drag thermopower in nanowires and bulk potassium crystals under the conditions of competition between the boundary and bulk mechanisms of phonon relaxation,” J. Phys.: Condens. Matter 31, 375701 (2019). https://doi.org/10.1088/1361-648x/ab271f
I. I. Kuleev and I. G. Kuleev, “Effect of anisotropy of elastic energy on the electron–phonon drag and temperature dependences of thermal emf in potassium crystals at low temperatures,” Phys. Met. Metallogr. 120, 1033–1039 (2019). https://doi.org/10.1134/S0031918X19110103
I. I. Kuleev and I. G. Kuleev, “The role of shear waves in electron–phonon drag in potassium crystals at low temperatures,” Phys. Met. Metallogr. 121, 921–928 (2020). https://doi.org/10.1134/s0031918x20100063
H. B. G. Casimir, “Note on the conduction of heat in crystals,” Physica 5, 495–500 (1938). https://doi.org/10.1016/s0031-8914(38)80162-2
A. K. McCurdy, H. J. Maris, and C. Elbaum, “Anisotropic heat conduction in cubic crystals in the boundary scattering regime,” Phys. Rev. B 2, 4077–4083 (1970). https://doi.org/10.1103/physrevb.2.4077
H. J. Maris, “Enhancement of heat pulses in crystals due to elastic anisotropy,” J. Acoust. Soc. Am. 50, 812–818 (1971). https://doi.org/10.1121/1.1912705
D. Li, Yi. Wu, P. Kim, L. Shi, P. Yang, and A. Majumdar, “Thermal conductivity of individual silicon nanowires,” Appl. Phys. Lett. 83, 2934–2936 (2003). https://doi.org/10.1063/1.1616981
W. Liu and M. Asheghi, “Phonon–boundary scattering in ultrathin single-crystal silicon layers,” Appl. Phys. Lett. 84, 3819–3821 (2004). https://doi.org/10.1063/1.1741039
M. Asheghi, M. N. Touzelbaev, K. E. Goodson, Y. K. Leung, and S. S. Wong, “Temperature-dependent thermal conductivity of single-crystal silicon layers in SOI substrates,” J. Heat Transfer 120, 30–36 (1998). https://doi.org/10.1115/1.2830059
M. Asheghi, Y. K. Leung, S. S. Wong, and K. E. Goodson, “Phonon-boundary scattering in thin silicon layers,” Appl. Phys. Lett. 71, 1798–1800 (1997). https://doi.org/10.1063/1.119402
A. D. McConnell and K. E. Goodson, “Thermal conduction in silicon micro- and nanostructures,” Annu. Rev. Heat Transfer 14, 129–168 (2005). https://doi.org/10.1615/annualrevheattransfer.v14.120
D. G. Cahill, P. V. Braun, G. Chen, D. R. Clarke, S. Fan, K. E. Goodson, P. Keblinski, W. P. King, G. D. Mahan, A. Majumdar, H. J. Maris, S. R. Phillpot, E. Pop, and L. Shi, “Nanoscale thermal transport. II. 2003–2012,” Appl. Phys. Rev. 1, 011305 (2003). https://doi.org/10.1063/1.4832615
I. G. Kuleyev, I. I. Kuleyev, and S. M. Bakharev, “Phonon focusing and temperature dependences of the thermal conductivity of silicon nanowires,” J. Exp. Theor. Phys. 118, 253–265 (2014). https://doi.org/10.1134/S1063776114020022
I. I. Kuleyev, S. M. Bakharev, I. G. Kuleyev, and V. V. Ustinov, “Phonon focusing and temperature dependences of thermal conductivity of silicon nanofilms,” J. Exp. Theor. Phys. 120, 638–650 (2015). https://doi.org/10.1134/S1063776115020144
I. G. Kuleyev, I. I. Kuleyev, S. M. Bakharev, and V. V. Ustinov, Phonon Focusing and Phonon Transport: In Single-Crystal Nanostructures, Texts and Monographs in Theoretical Physics (De Gruyter, Berlin, 2020). https://doi.org/10.1515/9783110670509
J. Ziman, Electrons and Phonons (Oxford Univ. Press, Oxford, 1960).
B. M. Mogilevskii and A. F. Chudnovskii, Heat Conductivity of Semiconductors (Nauka, Moscow, 1972).
R. Berman, Thermal Conduction in Solids (Oxford Univ. Press, Oxford, 1976).
M. Knudsen, “Die Gesetze der Molekularströmung und der inneren Reibungsströmung der Gase durch Röhren,” Ann. Phys. 333, 75–130 (1909). https://doi.org/10.1002/andp.19093330106
R. Berman, F. E. Simon, and J. M. Ziman, “The thermal conductivity of diamond at low temperatures,” Proc. R. Soc. London, Ser. A: Math. Phys. Sci. 220, 171–183 (1953). https://doi.org/10.1098/rspa.1953.0180
R. Berman, E. L. Foster, and J. M. Ziman, “Thermal conduction in artificial sapphire crystals at low temperatures I. Nearly perfect crystals,” Proc. R. Soc. London, Ser. A: Math. Phys. Sci. 231, 130–144 (1955). https://doi.org/10.1098/rspa.1955.0161
I. I. Kuleyev, I. G. Kuleyev, S. M. Bakharev, and A. V. Inyushkin, “Relaxation times and mean free paths of phonons in the boundary scattering regime for silicon single crystals,” Phys. Solid State 55, 31–44 (2013). https://doi.org/10.1134/S106378341301023X
I. I. Kuleyev, I. G. Kuleyev, S. M. Bakharev, and A. V. Inyushkin, “Features of phonon transport in silicon rods and thin plates in the boundary scattering regime. The effect of phonon focusing at low temperatures,” Phys. B: Condens. Matter 416, 81–87 (2013). https://doi.org/10.1016/j.physb.2013.02.020
I. I. Kuleyev, I. G. Kuleyev, S. M. Bakharev, and A. V. Inyushkin, “Effect of phonon focusing on the temperature dependence of thermal conductivity of silicon,” Phys. Status Solidi (b) 251, 991–1000 (2014). https://doi.org/10.1002/pssb.201350332
I. I. Kuleyev, I. G. Kuleyev, and S. M. Bakharev, “Phonon focusing and features of phonon transport in silicon nanofilms and nanowires at low temperatures,” Phys. Status Solidi (b) 252, 323–332 (2015). https://doi.org/10.1002/pssb.201451364
I. G. Kuleev and I. I. Kuleev, “Phonon focusing and electron transport in potassium monocrystals. Review 2,” Phys. Met. Metallogr. 124, Suppl. 1, S31–S58 (2023). https://doi.org/10.1134/S0031918X23602093
R. Fletcher, “Scattering of phonons by dislocations in potassium,” Phys. Rev. B 36, 3042–3051 (1987). https://doi.org/10.1103/physrevb.36.3042
I. G. Kuleyev and I. I. Kuleyev “The role of shear waves in electron–phonon relaxation and electrical resistivity of noble metals,” Chin. J. Phys. 83, 103–112 (2023). https://doi.org/10.1016/j.cjph.2022.12.010
I. I. Kuleyev and I. G. Kuleyev, “Phonon focusing and anisotropy of drag thermopower in potassium thin films at low temperatures,” J. Phys. Chem. Solids 170, 110948–110957 (2022). https://doi.org/10.1016/j.jpcs.2022.110948
F. J. Blatt, P. A. Schroeder, C. L. Foiles, and D. Greig, Thermoelectric Power of Metals (Plenum Press, New York, 1976). https://doi.org/10.1007/978-1-4613-4268-7
M. P. Zaitlin, L. M. Scherr, and A. C. Anderson, “Boundary scattering of phonons in noncrystalline materials,” Phys. Rev. B 12, 4487–4492 (1975). https://doi.org/10.1103/physrevb.12.4487
K. Fuchs, “The conductivity of thin metallic films according to the electron theory of metals,” Math. Proc. Cambridge Philos. Soc. 34, 100–108 (1938). https://doi.org/10.1017/s0305004100019952
E. H. Sondheimer, “The mean free path of electrons in metals,” Adv. Phys. 1, 1–42 (1952). https://doi.org/10.1080/00018735200101151
I. I. Kuleyev, I. G. Kuleyev, and S. M. Bakharev, “Low-temperature anisotropy of the thermal conductivity of single-crystal nanofilms and nanowires,” J. Exp. Theor. Phys. 119, 460–472 (2014). https://doi.org/10.1134/S1063776114090040
I. I. Kuleyev, S. M. Bakharev, I. G. Kuleyev, and V. V. Ustinov, “Influence of phonon focusing on the Knudsen flow of phonon gas in single-crystal nanofilms of spintronic materials,” Phys. Met. Metallogr. 118, 316–327 (2017). https://doi.org/10.1134/S0031918X17040068
M. Smoluchowski, “Zur kinetischen Theorie der Transpiration und Diffusion verdünnter Gase,” Ann. Phys. 338, 1559–1570 (1910). https://doi.org/10.1002/andp.19103381623
H. J. Maris and Sh.-I. Tamura, “Heat flow in nanostructures in the Casimir regime,” Phys. Rev. B 85, 54304 (2012). https://doi.org/10.1103/physrevb.85.054304
I. I. Kuleev, S. M. Bakharev, I. G. Kuleev, and V. V. Ustinov, “Effect of phonon focusing on Knudsen flow of phonon gas in single-crystal nanowires made of spintronics materials,” Phys. Met. Metallogr. 118, 10–20 (2017). https://doi.org/10.1134/s0031918x17010033
J. Philip and K. S. Viswanathan, “Phonon magnification in cubic crystals,” Phys. Rev. B 17, 4969–4978 (1978). https://doi.org/10.1103/physrevb.17.4969
A. G. Every, “Ballistic phonons and the shape of the ray surface in cubic crystals,” Phys. Rev. B 24, 3456–3467 (1981). https://doi.org/10.1103/physrevb.24.3456
C. Jasiukiewicz, T. Paszkiewicz, and D. Lehmann, “Phonon focussing patterns: Calculation of response of finite area detectors to pulsed ballistic beams of dispersive and dispersionless phonons,” Z. Phys. B Condens. Matter 96, 213–222 (1994). https://doi.org/10.1007/BF01313286
M. Lax and V. Narayanamurti, “Phonon magnification and the Gaussian curvature of the slowness surface in anisotropic media: Detector shape effects with application to GaAs,” Phys. Rev. B 22, 4876–4897 (1980). https://doi.org/10.1103/physrevb.22.4876
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This work was carried out as part of the state assignment of the Ministry of Education and Science of Russia (topic “Function”, no. 122021000035-6).
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This review is an English translation of Chapter 3 of the monograph: I.G. Kuleyev and I.I. Kuleyev, The Role of Quasi-Transverse Phonons and Elastic Anisotropy in Electrical Resistivity and Thermoelectric Effects in Alkali and Noble Metals (Ekaterinburg: UMTS UPI, 2023, p. 205. ISBN 978-5-8295-0882-1).
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Kuleyev, I.I., Kuleyev, I.G. Effect of Phonon Focusing and Shear Waves on Drag Thermopower in Potassium Single-Crystal Nanostructures at Low Temperatures. Review 3. Phys. Metals Metallogr. 124 (Suppl 1), S60–S86 (2023). https://doi.org/10.1134/S0031918X23602160
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DOI: https://doi.org/10.1134/S0031918X23602160