Magnetization Process of a Screw Spin System. II

Kitano, Yoshiharu; Nagamiya, Takeo

doi:10.1143/ptp.31.1

Cited by 134 publications

(22 citation statements)

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Order By: Relevance

“…For the above theory the transition field is expected to be of the order of (J (0) − J (q))/M (ref. 29), in agreement with the observed fields (M is the magnetic moment). For PrPtAl the energy dispersion of the lowest crystal field excitation gives an energy difference E(0) − E(q 1,2 ) ≈ 0.2 meV (Supplementary Information), which corresponds to a field in excess of 2 T. We find a much lower field is needed to suppress the modulated state, as described below.…”

Section: Nature Physics Doi: 101038/nphys3238supporting

confidence: 90%

Modulated magnetism in PrPtAl

et al. 2015

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The transition between paramagnetism and ferromagnetism is the paradigm for a continuous phase transition at finite temperature. When such a transition is tuned to zero temperature in clean materials, the growth of low-energy zero-point fluctuations potentially drives an array of phenomena, including the formation of novel states such as nonconventional superconductivity. Experimentally, the growth of the fluctuations, however, is curtailed and the transition becomes discontinuous as its temperature is reduced. This is understood to arise from non-analytic corrections to the free energy that always occur 1 . In a recent theory 2,3 , changes of the excitation spectrum are self-consistently considered alongside the ground state. This analysis reveals that a transition to a new state may be an alternative outcome. As the excitation spectrum (the 'disorder') is pivotal to promoting the new 'order' this mechanism is referred to as 'order by disorder'. Here, we report the discovery of modulated order in PrPtAl, consistent with complex spirals, at the boundary between paramagnetism and ferromagnetism, giving the first clear experimental realization of such a state.In our theoretical model, deformations of the Fermi surface in the modulated state enlarge the phase space available for low-energy particle-hole fluctuations and this self-consistently lowers the free energy relative to a uniform ferromagnetic state. Although previous theory predicting spiral formation 4,5 based on this mechanism has considered isotropic magnets, easy-plane systems are better candidate materials, as a hard magnetic axis provides a natural orientation for the spiral wavevector and suppresses 'unwanted' moment fluctuations along the spiral direction. The anisotropy can be introduced with local moments 6 , although the theoretical description close to a ferromagnetic quantum critical point 7 has only recently been extended to include the coupling of these moments to the conduction electrons 8 . Here we describe our findings for PrPtAl. This material is close to being an easy-plane ferromagnet, but has an additional magnetic anisotropy between the two easy axes in the plane. The electronic levels of the praseodymium 4f 2 Pr 3+ ions are split in the crystal environment (PrPtAl has an orthorhombic TiNiSn structure) into nine non-magnetic singlet states. Inelastic neutron studies 9 reveal clear crystal field excitations between these. Choosing a system with only singlets simplifies the theory considerably, avoiding Kondo lattice physics, while still introducing magnetic anisotropy.As there are no preformed moments, ferromagnetic order is achieved by mixing singlets via an inter-site exchange interaction 10 , a process referred to as induced-moment magnetism. Our theoretical approach to analysing the magnetic interactions that bring about magnetic order in PrPtAl differs from the standard treatment 11 by keeping the full frequency dependence of the fermion-mediated Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction. This is the key element for a descr...

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Section: Nature Physics Doi: 101038/nphys3238supporting

confidence: 90%

Modulated magnetism in PrPtAl

et al. 2015

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“…The modification of the spin screw structure due to the anisotropy energy and the applied magnetic field could be unambiguously interpreted with the theory of Kitano and Nagamiya [4].…”

Section: Introductionsupporting

confidence: 52%

A Wide Concentration Range Induced Moment System: (Tb_cLa_1−c)Be₁₃

Clad

Bouton

Herr

1980

Physica Status Solidi (b)

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“…Though below T N the a-axis susceptibility decreases faster than the one along the c axis, they both change in a similar fashion and in disparity with the relatively small decrease in the b-axis susceptibility. The observed finite values of the susceptibility along all crystallographic directions at low temperature differ qualitatively from those of the simple collinear antiferromagnet (where parallel susceptibility vanishes at low temperature) and are somewhat reminiscence of the susceptibility behavior in screw-type magnetic structures, 24 where both parallel and perpendicular components remain finite.…”

Section: A Bulk Magnetic Responsementioning

confidence: 71%

Neutron diffraction, magnetic, and magnetoelectric studies of phase transitions in multiferroic Mn0.90Co0.10WO
Urcelay-Olabarría
¹
,
Ressouche
²
,
Mukhin
³

et al. 2012
Phys. Rev. B
23
7
39
0
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We have studied various spontaneous and magnetic-field-induced phase transitions in single crystals of multiferroic Mn 0.9 Co 0.1 WO 4 using magnetic and magnetoelectric measurements and neutron diffraction. Compared to pure MnWO 4 , our data consistently confirm that the anisotropic Co 2+ ions induce reorientation of the spin cycloid structure to the ac plane and reveal P a and P c components of spontaneous electric polarization. Field-induced phase transitions accompanied by anomalies of magnetic susceptibility and suppression of both P a and P c polarizations have been observed for H c (∼3 T) and H a (∼8.5 T). Neutron diffraction has revealed that in both cases the spin cycloid plane flops in direction almost perpendicular to H , i.e., close to the ab and bc planes, respectively. Parameters describing the magnetic structures including wave vectors, orientations of the main elliptical axes, etc., have been determined in all spontaneous and field-induced states.

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Magnetization Process of a Screw Spin System. II

Cited by 134 publications

References 0 publications

Modulated magnetism in PrPtAl

Modulated magnetism in PrPtAl

A Wide Concentration Range Induced Moment System: (Tb_cLa_1−c)Be₁₃

Neutron diffraction, magnetic, and magnetoelectric studies of phase transitions in multiferroic Mn0.90Co0.10WO
Urcelay-Olabarría
¹
,
Ressouche
²
,
Mukhin
³

et al. 2012
Phys. Rev. B
23
7
39
0
View full text Add to dashboard Cite

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Magnetization Process of a Screw Spin System. II

Cited by 134 publications

References 0 publications

Modulated magnetism in PrPtAl

Modulated magnetism in PrPtAl

A Wide Concentration Range Induced Moment System: (TbcLa1−c)Be13

Neutron diffraction, magnetic, and magnetoelectric studies of phase transitions in multiferroic Mn0.90Co0.10WOUrcelay-Olabarría1, Ressouche2, Mukhin3 et al. 2012Phys. Rev. B237390View full textAdd to dashboardCite

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A Wide Concentration Range Induced Moment System: (Tb_cLa_1−c)Be₁₃

Neutron diffraction, magnetic, and magnetoelectric studies of phase transitions in multiferroic Mn0.90Co0.10WO
Urcelay-Olabarría
¹
,
Ressouche
²
,
Mukhin
³

et al. 2012
Phys. Rev. B
23
7
39
0
View full text Add to dashboard Cite