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- Artyukhin, Sergey, et al.
(author)
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Solitonic lattice and Yukawa forces in the rare-earth orthoferrite TbFeO3
- 2012
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In: Nature Materials. - 1476-4660. ; 11:8, s. 694-699
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Journal article (peer-reviewed)abstract
- The random fluctuations of spins give rise to many interesting physical phenomena, such as the 'order-from-disorder' arising in frustrated magnets and unconventional Cooper pairing in magnetic superconductors. Here we show that the exchange of spin waves between extended topological defects, such as domain walls, can result in novel magnetic states. We report the discovery of an unusual incommensurate phase in the orthoferrite TbFeO3 using neutron diffraction under an applied magnetic field. The magnetic modulation has a very long period of 340 angstrom at 3 K and exhibits an anomalously large number of higher-order harmonics. These domain walls are formed by Ising-like Tb spins. They interact by exchanging magnons propagating through the Fe magnetic sublattice. The resulting force between the domain walls has a rather long range that determines the period of the incommensurate state and is analogous to the pion-mediated Yukawa interaction between protons and neutrons in nuclei.
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- Viskadourakis, Z., et al.
(author)
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Low-temperature ferroelectric phase and magnetoelectric coupling in underdoped La2CuO4+x
- 2012
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In: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 85:21
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Journal article (peer-reviewed)abstract
- We report the discovery of ferroelectricity below 4.5 K in highly underdoped La2CuO4+x accompanied by slow charge dynamics which develop below T similar to 40 K. An anisotropic magnetoelectric response has also been observed, indicating considerable spin-charge coupling in this lightly doped parent high-temperature copper-oxide superconductor. The ferroelectric state is proposed to develop from polar nanoregions, in which spatial inversion symmetry is locally broken due to nonstoichiometric carrier doping.
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