Magnetic-polaron-driven magnetoresistance in the pyrochloreLu2V2O7

Abstract

The structural, magnetic, and transport properties of single-crystalline Lu 2 V 2 O 7 are studied. Lu 2 V 2 O 7 shows a ferromagnetic transition at T C = 69.5 K and a negative magnetoresistance ͑MR͒ as high as 50% at T 2 = 75 K with an applied field of 5 T. Through various experiments, it is demonstrated that the mechanism for MR is not through double exchange, but through a polaron-mediated behavior similar to Tl 2 Mn 2 O 7 . This places Lu 2 V 2 O 7 as the only other example of polaron-mediated MR among the pyrochlore oxides.

Spin-Wave Spectrum of the Quantum Ferromagnet on the Pyrochlore LatticeLu2V2O7Mena1, Perry2, Perring3 et al. 2014Phys. Rev. Lett.554423View full textAdd to dashboardCite

“…Measurements of the thermal conductivity in Lu 2 V 2 O 7 by Onose et al have been interpreted in terms of a magnon Hall effect [1], based on the observation that the thermal conductivity has a distinctive dependence on applied magnetic fields for temperatures below T C . This highly unusual and previously unreported phenomenon was shown to be consistent with a model in which the Dzyaloshinskii-Moriya interaction (DMI) between nearest neighbour spins deflects magnon wavepackets propagating from the hot to the cold side of the sample [1].Further evidence of the exceptional properties of Lu 2 V 2 O 7 was provided by Zhou et al [13] who discovered that it displays a large (50%) magneto-resistance around 70 K in an applied magnetic field. Additionally, polarised neutron diffraction found evidence for an orbital ordered ground state with associated super-exchange pathways favouring a dominant nearest-neighbour ferromagnetic coupling [14].…”

“…Further evidence of the exceptional properties of Lu 2 V 2 O 7 was provided by Zhou et al [13] who discovered that it displays a large (50%) magneto-resistance around 70 K in an applied magnetic field. Additionally, polarised neutron diffraction found evidence for an orbital ordered ground state with associated super-exchange pathways favouring a dominant nearest-neighbour ferromagnetic coupling [14].…”

Geometrically Frustrated Magnetic Materials

“…This material is actually a ferromagnetic insulator with T c ¼ 74 K. [154] While it is not, thus, frustrated in the normal sense, it exhibits some unusual properties such as orbital ordering [155] and a negative magnetoresistance. [156] The final compound in the B-site only series is Y 2 Mn 2 O 7 based on Mn 4þ which has configuration 3d 3 (t 2g 3 ) with S ¼ 3/2. The manganate(4þ) pyrochlores, unlike the perovskites of the same ion are not stable at ambient pressure, Figure 2.35.…”

Single-ion anisotropy, Dzyaloshinskii-Moriya interaction, and negative magnetoresistance of the spin-12pyrochloreR2VXiang1, Kan2, Whangbo3 et al. 2011Phys. Rev. B424260View full textAdd to dashboardCite

“…3(a) of Ref. 9 ]. We note that this new mechanism of negative MR should be also applicable to other ferromagnetic insulators (e.g., EuO).…”