Electrons with Planckian scattering obey standard orbital motion in a magnetic field

In various so-called strange metals, electrons undergo Planckian dissipation^1,2, a strong and anomalous scattering that grows linearly with temperature³, in contrast to the quadratic temperature dependence expected from the standard theory of metals. In some cuprates^4,5 and pnictides⁶, a linear dependence of resistivity on a magnetic field has also been considered anomalous—possibly an additional facet of Planckian dissipation. Here we show that the resistivity of the cuprate strange metals Nd_0.4La_1.6−xSr_xCuO₄ (ref. ⁷) and La_2−xSr_xCuO₄ (ref. ⁸) is quantitatively consistent with the standard Boltzmann theory of electron motion in a magnetic field, in all aspects—field strength, field direction, temperature and disorder level. The linear field dependence is found to be simply the consequence of scattering rate anisotropy. We conclude that Planckian dissipation is anomalous in its temperature dependence, but not in its field dependence. The scattering rate in these cuprates does not depend on field, which means that their Planckian dissipation is robust against fields up to at least 85 T.