Pressure-induced commensurate order in TbMn2O5 and DyMn2O5 : Influen

Abstract

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Tuning competing magnetic interactions with pressure in RMn2O5 multiferroics

“…Above a pressure of about 5 GPa, the HT-ICM phase is replaced by a PCM phase with a propagation vector q PCM = ( 1 2 , 0, 1 2 )). This phase is similar to the one observed in YMn 2 O 5 23 , PrMn 2 O 5 25 , DyMn 2 O 5 , TbMn 2 O 5 26 and similar to the one we have observed in GdMn 2 O 5 . This PCM phase is stabilized in the entire temperature range below T 1 (p) and coexists with the CM phase below T 2 (p).…”

“…As shown in Figure 3, at 8.4 GPa, when temperature above 32 K, the PCM start to appear with the disappearance of the CM phase. The magnetic propagation wave vector of this new pressure induced phase is indexed with the same propagation vector q= ( 1 2 , 0, 1 2 ) as the PCM phase reported in several other members of the family 23,25,26 and will be labeled PCM phase in the following. The deduced phase diagram from the combination of all our data is summarized in Figure 4.…”

Pressure-dependent X-ray diffraction of the multiferroics RMn2O5

“…Indeed, an increase in J 1 favors an AFM ordering between neighboring Mn 4+ ions that is a 1 2 component along the c axis. This could lead to the PCM phase, which has recently been discovered under pressure in the R = Y, Tb, Pr and Dy compounds (Deutsch et al, 2015(Deutsch et al, , 2018Peng et al, 2017). It is important to note that compounds with nonmagnetic R 3+ ions such as in BiMn 2 O 5 (Muñ oz et al, 2002) do not encounter frustration due to the J 6 interactions.…”

“…In these complex systems, the large effect of small variations in the interatomic distances and angles on the super-exchange integrals induces a strong dependence of the multiferroic properties on external factors. Indeed, an enhanced polarization has been observed under pressure (de la Cruz et al, 2006;Chaudhury et al, 2008) in the RMn 2 O 5 (R = Tb, Ho and Y) compounds and it has been associated with a new pressure-induced magnetic phase, recently shown by neutron measurements on Y (Deutsch et al, 2015;Kozlenko et al, 2015), Tb (Deutsch et al, 2018) and PrMn 2 O 5 (Peng et al, 2017). The dependence of the electric polarization of RMn 2 O 5 at ambient pressure as a function of the ionic radius of R 3+ .…”

4f spin driven ferroelectric-ferromagnetic multiferroicity in PrMn2O5 under a magnetic field

“…This result portrays the dominant role of the 3d ions and their frustrated superexchange interactions in the emergence of the spin driven ferroelectricity. Although known for a few other multiferroics [4,6,26], in RMn 2 O 5 , the role of the 4 f ions was revealed only recently to explain the magnetoelectric behaviors in some candidates [27,28]. Particularly in GdMn 2 O 5 and NdMn 2 O 5 , in addition to the dominant 3d-3d effect, a weak 3d-4 f interaction was proposed to explain the observed spin driven ferroelectricity [15,29].…”