dc.description.abstract
Tuning materials properties on demand is at the heart of condensed matter science. Electronic transport and magnetism are strongly linked to the overlap of electronic wave functions and can be, thus, manipulated by varying the electronic bandwidth through chemical substitution or physical pressure. However, a controlled tuning of the symmetry and anisotropy of transfer integrals and exchange interactions remained inaccessible so far. Here, we apply compression and tension to single crystalline samples to explore systems with strong electronic interactions.
Geometrical frustration suppresses magnetic order down to very low temperatures TN << J [1] or entirely [2,3]. Utilizing the recent advancements in strain tuning of the unconventional superconductor Sr2RuO4 [4-6], we apply uniaxial stress to a triangular-lattice compound enabling us to tune the Mott transition and unconventional superconductivity with unprecedented precision. This way, we pinpoint the nonmagnetic ground state of one of the hottest quantum-spin-liquid candidates through the slope of its metal-insulator boundary in the temperature-pressure phase diagram [2,3]. Moreover, we obtain direct control of antiferromagnetic order within one kagome-lattice single crystal by applying in situ uniaxial strain [2]. Breaking the symmetry in a controlled manner yields a linear increase of TN by 10% as stress reduces the frustration strength, in line with theoretical predictions for a distorted kagome lattice. Our pioneering endeavors [1,2,5-7] demonstrate uniaxial strain as a powerful tool to tune correlated electrons in situ between insulating, (non)magnetic, metallic and superconducting states – towards stabilizing novel, exotic, possibly even quantum entangled phases.
In the end, I provide a glimpse into utilization of bandwidth tuning in the applied physics: we achieved a new world record in thermoelectric power factor in NiAu alloys by tuning electronic interband scattering through negative chemical pressure [8].
[1] Jierong Wang, Y.-S. Su, M. Spitaler, K.M. Zoch, C. Krellner, P. Puphal, S.E. Brown, and A. Pustogow, Phys. Rev. Lett. 131, 256501 (2023)
[2] A. Pustogow, Y. Kawasugi, H. Sakurakoji, and N. Tajima, Nat. Commun. 14, 1960 (2023)
[3] B. Miksch, A. Pustogow, M. Javaheri Rahim, A. A. Bardin, K. Kanoda, J. A. Schlueter, R. Hübner, M. Scheffler, and M. Dressel, Science 372, 276-279 (2021)
[5] Y. Luo, A. Pustogow, P. Guzman, A. P. Dioguardi, S. M. Thomas, F. Ronning, N. Kikugawa, D. A. Sokolov, F. Jerzembeck, A. P. Mackenzie, C.W. Hicks, E. D. Bauer, I. I. Mazin, and S. E. Brown, Phys. Rev. X 9, 021044 (2019)
[6] A. Pustogow, Y. Luo, A. Chronister, Y.-S. Su, D. A. Sokolov, F. Jerzembeck, A. P. Mackenzie, C. W. Hicks, N. Kikugawa, S. Raghu, E. D. Bauer, and S. E. Brown, Nature 574, 72–75 (2019)
[7] A. Chronister, M. Zingl, A. Pustogow, Y. Luo, D. A. Sokolov, N. Kikugawa, C. W. Hicks, F. Jerzembeck, J. Mravlje, E. D. Bauer, A. P. Mackenzie, A. Georges, and S. E. Brown, npj Quantum Materials 7, 113 (2022)
[8] F. Garmroudi, M. Parzer, A. Riss, C. Bourgès, S. Khmelevskyi, T. Mori, E. Bauer, and A. Pustogow, Sci. Adv. 9, abc123456 (2023)
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