Ferroquadrupolar ordering in PrTi<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>Al<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>20</mml:mn></mml:msub></mml:math>

Sato, Taku; Ibuka, Soshi; Nambu, Yusuke; Yamazaki, T.; Hong, Tao; Sakai, Akito; Nakatsuji, Satoru

doi:10.1103/physrevb.86.184419

Cited by 100 publications

(106 citation statements)

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“…Most of them are considered to be antiferro quadrupole ordered phases. An exception is PrTi 2 Al 20 , 10,11) and the neutron scattering 15) and ultrasound experiments 16) suggest a ferro * E-mail: hattori@tmu.ac.jp quadrupole order in this compound. Anisotropy in the orbital sector in these systems is manifested in the strong anisotropy of the critical field and the phase diagram strongly dependent on the field direction.…”

Section: Introductionmentioning

confidence: 97%

Classical Monte Carlo Study for Antiferro Quadrupole Orders in a Diamond Lattice

Hattori

Tsunetsugu

2016

J. Phys. Soc. Jpn.

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We investigate antiferro quadrupole orders in a diamond lattice under magnetic fields by Monte Carlo simulations for two types of classical effective models. One is an XY model with Z3 anisotropy, and the other is a two-component φ 4 model with a third-order anisotropy. We confirm that the universality class of the zero-field transition is that for the three-dimensional XY model. Magnetic field corresponds to a Z3 field in the effective model, and under this field, we find that collinear and canted antiferro-quadrupole orders compete. Each phase is characterized by symmetry breaking in the sector of (sublattice Z2)⊗(reflection Z2 for the order parameter). When Z3 anisotropy and magnetic field vary, it turns out that this system is a good playground for various multicritical points; bicritical and tetracritical points emerge in a finite field. Another important finding is about the scaling of parasitic ferro quadrupole order at the zero-field critical point. This is the secondary order parameter induced by the primary antiferro order, and its critical exponent β ′ =0.815 clearly differs from the expected value that is twice the value for the primary order parameter. The corresponding correlation length exponent is also different, ν ′ =0.597(12). We also discuss relation of the present effective quadrupole models with the 3-state Potts model as well as implication to undertanding of orbital orders in Pr-based 1-2-20 compounds.

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Section: Introductionmentioning

confidence: 97%

Classical Monte Carlo Study for Antiferro Quadrupole Orders in a Diamond Lattice

Hattori

Tsunetsugu

2016

J. Phys. Soc. Jpn.

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“…To check this possibility, one needs to examine, for example, the reflection at (200), which has not been discussed. 30) (The authors have been recently informed that unpublished data confirmed the absence of the (200) reflection. 32) ) We emphasize that our NMR results exclude any type of AFQ order, in which Pr sites are divided into two sublattices with the opposite sign of the quadrupole, O 20 or O 22 .…”

mentioning

confidence: 98%

“…19) These results are consistent with the CEF level scheme deduced from inelastic neutron scattering experiments, which determined the energies between the ground Γ 3 level and the excited Γ 4 , Γ 5 , and Γ 1 levels to be 65, 108, and 156 K, respectively. 30) A phase transition was detected by a peak in the specific heat near 2 K. 19) A clear anomaly in ultrasonic measurement 31) combined with the absence of an anomaly in the magnetic susceptibility 19) indicates that this is a quadrupole transition. Neutron diffraction measurements in magnetic fields along 100 revealed a sudden increase in the intensity of allowed nuclear Bragg peaks across the transition due to field-induced dipole moments.…”

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confidence: 99%

“…[21][22][23][24][25][26] Various measurements indicate that the Al-based materials are characterized by stronger hybridization between conduction and f electrons than the Zn-based materials, leading to anomalous transport properties and their pronounced pressure depen- * E-mail : taka.taniguchi@issp.u-tokyo.ac.jp dence. 4,[23][24][25][26][27][28][29][30] In this paper, we focus on PrTi 2 Al 20 . The magnetic susceptibility for H 111 is nearly independent of temperature below 20 K, indicating van Vleck paramagnetism with a nonmagnetic CEF ground state.…”

mentioning

confidence: 99%

“…Neutron diffraction measurements in magnetic fields along 100 revealed a sudden increase in the intensity of allowed nuclear Bragg peaks across the transition due to field-induced dipole moments. 30) The results were considered as evidence 27 Al-NMR experiments. 28) Here, we report the results of 27 Al-NMR measurements on a single crystal of PrTi 2 Al 20 in the quadrupole ordered phase.…”

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confidence: 99%

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NMR Observation of Ferro-Quadrupole Order in PrTi₂Al₂₀

et al. 2016

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We report the results of 27 Al-NMR measurements on a single crystal of PrTi 2 Al 20 . This compound shows a phase transition near 2 K associated with the quadrupole degree of freedom of Pr ions, for which the ground state of the crystalline electric field is a nonmagnetic doublet. When a magnetic field is applied along the 111 direction, the NMR lines split upon entering the low-temperature phase, indicating the breaking of the three fold rotation symmetry due to the field-induced magnetic dipole perpendicular to the field. This provides microscopic evidence for a ferro order of the O 20 quadrupole. Although a first-order transition is expected theoretically, the line splitting evolves continuously within the experimental resolution.KEYWORDS: PrTi 2 Al 20 , NMR, quadrupole order, symmetry breaking Multipoles of f electrons in rare-earth compounds show a wide variety of phenomena. [1][2][3][4] In particular, non-Kramers rare-earth ions with an even number of f electrons in a cubic environment have been attracting strong interest recently. [5][6][7][8][9][10][11] In these systems, it is possible that the ground states of the J multiplet split by the cubic crystalline electric field (CEF) are nonmagnetic, i.e., the matrix elements of the magnetic dipole J are identically zero, yet have a degeneracy that allows active higher-order multipoles such as electric quadrupoles or magnetic octupoles. Then various interesting phenomena such as multipole orders [12][13][14] or multichannel Kondo effects 15,16) are expected at low temperatures.These possibilities have indeed been realized in compounds containing Pr 3+ ions with the 4 f 2 electronic configuration. The nine states of the J = 4 ground multiplet are split by a cubic CEF into the Γ 1 nonmagnetic singlet, the Γ 3 nonmagnetic doublet, the Γ 4 magnetic triplet, and the Γ 5 magnetic triplet. If the CEF ground state is the Γ 3 doublet, we encounter an interesting situation that the ground state is nonmagnetic but has nonzero matrix elements for the two types of quadrupoles, O 20 = (3J 2 z −J 2 )/2 and O 22 = √ 3(J 2 x −J 2 y )/2, and one octupole T xyz = ( √ 15/6)J x J y J z , where the bar represents the sum over the possible permutations of the indices x, y, and z. 13) The series of compounds PrT 2 X 20 (T : transition metal, X: Zn or Al) provides particularly interesting examples of the Γ 3 CEF ground states. 4) As shown in Fig. 1 [18][19][20][21] all of which also show superconductivity. [21][22][23][24][25][26] Various measurements indicate that the Al-based materials are characterized by stronger hybridization between conduction and f electrons than the Zn-based materials, leading to anomalous transport properties and their pronounced pressure depen- * E-mail : taka.taniguchi@issp.u-tokyo.ac.jp dence. 4,[23][24][25][26][27][28][29][30] In this paper, we focus on PrTi 2 Al 20 . The magnetic susceptibility for H 111 is nearly independent of temperature below 20 K, indicating van Vleck paramagnetism with a nonmagnetic CEF ground state. 29) Specific heat measurements ...

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Composite electronic orders induced by orbital Kondo effect

Kuramoto

2016

Science Bulletin

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In a large number of rare-earth and actinide systems, Kondo effect tends to suppress magnetic order by making the spin singlet between localized and conduction electron spins. In the presence of orbital degrees of freedom, however, there emerge exotic electronic orders induced by Kondo effect. The orbital Kondo effect can collectively make diagonal and off-diagonal (superconducting) orders. With the particle-hole symmetry in conduction bands, these orders are all degenerate, forming a macroscopic SO(5) multiplet. This paper discusses recent theoretical development on these electronic orders which are relevant to Pr 3+ and U 4+ systems with even number of f electrons per site. In the superconducting order, each conduction-electron pair is coupled with local degrees of freedom, forming a composite entity with a staggered spatial pattern. The quasi-particle spectrum is best interpreted as virtual hybridization with resonant states at the Fermi level. Possible order parameter for URu2Si2 in the hidden order state is discussed in the context of composite orders. Briefly discussed are related issues such as homogeneous odd-frequency pairing and SO(5) theory for high-temperature superconductors.

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Ferroquadrupolar ordering in PrTi2Al20

Cited by 100 publications

References 25 publications

Classical Monte Carlo Study for Antiferro Quadrupole Orders in a Diamond Lattice

Classical Monte Carlo Study for Antiferro Quadrupole Orders in a Diamond Lattice

NMR Observation of Ferro-Quadrupole Order in PrTi₂Al₂₀

Composite electronic orders induced by orbital Kondo effect

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Ferroquadrupolar ordering in PrTi2Al20

Cited by 100 publications

References 25 publications

Classical Monte Carlo Study for Antiferro Quadrupole Orders in a Diamond Lattice

Classical Monte Carlo Study for Antiferro Quadrupole Orders in a Diamond Lattice

NMR Observation of Ferro-Quadrupole Order in PrTi2Al20

Composite electronic orders induced by orbital Kondo effect

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Product

Resources

About

NMR Observation of Ferro-Quadrupole Order in PrTi₂Al₂₀