The 100 tesla magnet system at the National Laboratory of Intense Magnetic Fields in Toulouse, France. Credit: Nanda Gonzague.
Strange metals, or non-Fermi liquids, are distinct states of matter that have been observed in different quantum materials, including cuprate superconductors. These states are characterized by unusual conductive properties, such as resistivity linearly related to temperature (J-linear).
In the strange metallic phase of matter, electrons experience what is known as “Planck dissipation”, a high diffusion rate that increases linearly as temperature increases. This strong T-linear electron scattering is anomalous for metals, which typically exhibit a quadratic temperature dependence (T2), as predicted by standard metal theory.
Researchers from the University of Sherbrooke in Canada, the Laboratoire National des Champs Magnétiques Intenses in France and other institutes around the world recently conducted a study exploring the possibility that the resistivity of strange metals is not only associated with temperature. , but also to an applied magnetic field. . This magnetic field linearity had previously been observed in some cuprates and pnictides, with some physicists suggesting that it might also be related to Planckian dissipation.
The researchers conducted their experiments on two specific cuprate strange metals, namely Nd0.4The1.6−XsrXCuO4 and The2−XsrXCuO4. Their findings, published in Natural Physicssuggest that the resistivity of these two strange metals is consistent with predictions of the standard Boltzmann theory of the motion of electrons in a magnetic field in all ways, showing no anomalies associated with Planckian dissipation.
“We wanted to investigate the field dependence of the Planck scattering rate in the odd metallic phase of cuprate superconductors, especially in NdLSCO, whose scattering rate had previously been measured with angle-dependent magnetoresistance (ADMR) experiments. ),” said Amirreza Ataei, one of the researchers. who carried out the study, told Phys.org. “In this material, due to a relatively low critical temperature, Tc, we had access to one of the largest measurement ranges of B-linear resistivity and were able to reproduce magnetoresistance over this magnetic field range using standard Boltzmann theory.”
The sample holder that was used for the high field measurements in Toulouse. The length of the black single crystal sample is less than 2 mm, the contacts were made with silver epoxy and 25 micrometer wires, and the sample is mounted on a sapphire plate Credit: Ataei M .Sc. thesis https://savoirs.usherbrooke.ca/handle/11143/15285
A key goal of recent work by Ataei and co-workers was to determine whether the in-plane magnetoresistance in the strange metallic phase of namely Nd0.4The1.6−XsrXCuO4 and The2−XsrXCuO4 was abnormal in cases where the magnetic field and the electric current were in parallel. Ultimately, the metrics they collected suggest that was not the case.
“We expect our findings to have a big impact in the field of Planckian dissipation, a major mystery in condensed matter physics with intriguing connections to black hole physics,” Ataei explained. “We show that this enigmatic phenomenon is insensitive to the magnetic field, up to 85 T, one of the highest attainable magnetic fields in the world.
Louis Taillefer, Cyril Proust and Seyed Amirreza Ataei. Credit: Michel Caron – UdeS.
Overall, the results collected by this team of researchers seem to call into question the hypothesis according to which the linear dependence of the resistivity to a magnetic field observed in certain strange metals is associated with Planckian dissipation. In contrast, their experimental data suggest that the Planckian dissipation is anomalous only in its temperature dependence, while its field dependence is aligned with standard theoretical predictions.
“We now plan to extend the scope of this research to different quantum materials in or near the strange metallic phase,” Ataei added.
A new look at metals reveals a ‘strange’ similarity
Amirreza Ataei et al, Planckian scattering electrons obey standard orbital motion in a magnetic field, Natural Physics (2022). DOI: 10.1038/s41567-022-01763-0
JAN Bruin et al, Similarity of diffusion rates in metals showing linear resistivity T, Science (2013). DOI: 10.1126/science.1227612
Sean A. Hartnoll, Universal Incoherent Metallic Transport Theory, Natural Physics (2014). DOI: 10.1038/nphys3174
Subir Sachdev, Bekenstein-Hawking Entropy and Strange Metals, Physical examination X (2015). DOI: 10.1103/PhysRevX.5.041025
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Quote: Electrons with Planckian scattering in strange metals follow the standard rules of orbital motion in a magnet (2022, October 28) retrieved October 29, 2022 from https://phys.org/news/2022-10-electrons-planckian- strange-metals-standard.html
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