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Benoit Fauqué1

1, ESPCI Paris, Paris, , France

Large unsaturated magnetoresistance has been recently reported in numerous semi-metals [1].
Many of them have a topologically non-trivial band dispersion, such as Weyl nodes or lines.
In the first part of my presentation I will show that elemental antimony displays the largest high-field
magnetoresistance among all known semi-metals. I will present a detailed study of the angledependent
magnetoresistance and use a semi-classical framework invoking an anisotropic
mobility tensor to fit the data [2]. A slight deviation from perfect compensation and a modest
variation with magnetic field of the components of the mobility tensor are required to attain perfect
fits at arbitrary strength and orientation of magnetic field in the entire temperature window of study.
In the second part I will discuss the case of lightly doped SrTiO3-x [3]. At low temperature we find
that SrTiO3-x displays a large transverse (j⊥B) but also longitudinal (j//B) magnetoresistance which
can be captured, like in the case of the semi-metals, by a semi-classical framework including a
field dependent mobility carriers.
Our results demonstrate that large orbital magnetoresistance is an unavoidable consequence of
low carrier concentration and the sub-quadratic magnetoresistance seen in many semi-metals and
doped semi-conductors can be attributed to field-dependent mobility, expected whenever the
disorder length-scale exceeds the Fermi wavelength [4].
[1] M. N. Ali and al., Nature, 514, 205–208 (2014).
[2] B. Fauqué, Phys. Rev Mat. (2018), in press
[3] C. Collignon and al., unpublished
[4] J.C Song and al., Phys. Rev. B, 92, 1-5 (2015)

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