Dynamic spin fluctuations in the frustrated 
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-site spinel 
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Cho, Hwanbeom; Nirmala, R.; Jeong, Jaehong; Baker, Peter J.; Takeda, Hikaru; Mera, Nobuyoshi; Blundell, Stephen J.; Takigawa, Masaharu; Adroja, D. T.; Park, Je‐Geun

doi:10.1103/physrevb.102.014439

Cited by 10 publications

(12 citation statements)

References 49 publications

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“…In all cases the FC susceptibility curve continues to increase below the bifurcation temperature suggesting a portion of the spins not participating in the glassy dynamics. This is consistent with the interpretation suggested by Cho et al 13 for CuAl 2 O 4 that a dynamic and glassy phase coexist with the glassy phase corresponding to the degree of site disorder. Further, the applied magnetic field dependent bifurcation temperature deviates from the mean field AT line.…”

Section: Summary and Discussionsupporting

confidence: 93%

“…Parameters derived from this model fit within ranges for both insulating spin glasses and cluster glasses, although with the higher spin flip times reported in Table 3 we lean towards an insulating spin glass. Therefore, we believe the best interpretation of our solid solution from this analysis is that of a spin glass-like system shifting from a dilute diamond lattice to a dilute pyrochlore as Al is replaced with Ga 13 , 45 , with weaker frustration as Cu 2+ shifts to the pyrochlore lattice and bond length increases.…”

Section: Summary and Discussionmentioning

confidence: 90%

“…However, muon spin resonance (µSR) reveals a non-frozen state with significant dynamic spin fluctuation below the spin glass-like freezing transition. Site dislocation plays a role in introducing glassy behavior, but nevertheless spin fluctuations associated with the liquid state persists 13 . Prior investigation of this end member show that there is some inter-site mixing, with , indicating that the Cu 2+ ions primarily populate the diamond sublattice 14 .…”

Section: Introductionmentioning

confidence: 99%

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Magnetic and structural properties of the solid solution CuAl2(1−x)Ga2xO4

Bullard

Susner

Taddei

et al. 2021

Sci Rep

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CuAl2O4 is a ternary oxide spinel with Cu2+ ions ($$s=1/2$$ s = 1 / 2 ) primarily populating the A-site diamond sublattice. The compound is reported to display evidence of spin glass behavior but possess a non-frozen magnetic ground state below the transition temperature. On the other hand, the spinel CuGa2O4 displays spin glass behavior at ~ 2.5 K with Cu2+ ions more readily tending to the B-site pyrochlore sublattice. Therefore, we investigate the magnetic and structural properties of the solid solution CuAl2(1-x)Ga2xO4 examining the evolution of the magnetic behavior as Al3+ is replaced with a much larger Ga3+ ion. Our results show that the Cu2+ ions tend to migrate from tetrahedral to octahedral sites as the Ga3+ ion concentration increases, resulting in a concomitant change in the glassy magnetic properties of the solution. Results indicate glassy behavior for much of the solution with a general trend towards decreasing magnetic frustration as the Cu2+ ion shifts to the B-site. However, the $$x=0.1$$ x = 0.1 and 0.2 members of the system do not show glassy behavior down to our measurement limit (1.9 K) suggesting a delayed spin glass transition. We suggest that these two members are additional candidates for investigation to access highly frustrated exotic quantum states.

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Section: Summary and Discussionsupporting

confidence: 93%

Section: Summary and Discussionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

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Magnetic and structural properties of the solid solution CuAl2(1−x)Ga2xO4

Bullard

Susner

Taddei

et al. 2021

Sci Rep

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“…Our previous experimental works [18,19] and theoretical study [20,21] suggested a cuprate system CuAl2O4 (with Cu 2+ in tetrahedra, having e 4 t2 5 electron configuration) as a strong candidate hosting the Jeff=1/2 state. As the Cu 2+ ion has the largest U and λ, among other magnetic 3d transition metals [4,5], the cuprate compound would be an excellent example to introduce the SOE state with a strong correlation.…”

mentioning

confidence: 97%

“…CuAl2O4 has a spinel structure (Fig. 1a), where Cu 2+ is located at the center of the tetrahedron (A-site) [18,19]. Al 3+ sits at the center of the octahedra that consists of six neighboring oxygen ions (B-site).…”

mentioning

confidence: 99%

Pressure-induced transition from Jeff=1/2 to S=1/2 states in
Cho
¹
,
Kim
²
,
Lee
³

et al. 2021
Phys. Rev. B
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The spin-orbit entangled (SOE) Jeff-state has been a fertile ground to study novel quantum phenomena. Contrary to the conventional weakly correlated Jeff=1/2 state of 4d and 5d transition metal compounds, the ground state of CuAl2O4 hosts a Jeff=1/2 state with a strong correlation of Coulomb U. Here, we report that surprisingly Cu 2+ ions of CuAl2O4 overcome the otherwise usually strong Jahn-Teller distortion and instead stabilize the SOE state, although the cuprate has relatively small spin-orbit coupling. From the x-ray absorption spectroscopy and high-pressure x-ray diffraction studies, we obtained definite evidence of the Jeff=1/2 state with a cubic lattice at ambient pressure. We also found the pressure-induced structural transition to a compressed tetragonal lattice consisting of the spin-only S=1/2 state for pressure higher than Pc=8 GPa. This phase transition from the Mott insulating Jeff=1/2 to the S=1/2 states is a unique phenomenon and has not been reported before. Our study offers a rare example of the SOE Jeff-state under strong electron correlation and its pressure-induced transition to the S=1/2 state.

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High-Pressure Synthesis, Crystal Structure, and Physical Properties of a Spinel Compound Co_0.7Al₂S₄

Duan,

Wei,

Feng

et al. 2023

Inorg. Chem.

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In this paper, we report on the discovery of a spinel compound, Co 0.7 Al 2 S 4 , which was synthesized at high-pressure. The systematic characterizations were carried out by structural, magnetic, and heat capacity measurements. The compound crystallizes into a cubic structure with the space group Fd3̅ m (no. 227) and the lattice constant a = 9.9580(1) Å. Magnetic susceptibility measurements suggest that Co 0.7 Al 2 S 4 exhibits a spin glass ground state, freezing at T f ∼ 7.2 K with a Weiss temperature T θ ∼ −115.9 K, which is verified by ac magnetic susceptibility and heat capacity measurements. The frustration parameter f for Co 0.7 Al 2 S 4 is calculated to be about 16.6, based on the formula f = | T θ /T f |, indicating that Co 0.7 Al 2 S 4 is a high-frustration magnet. Specific heat data displays a T 2 dependence below the freezing temperature, which is different from the linear dependence observed in a common spin glass system. Compared with the similar compound CoAl 2 O 4 , it is suggested that the vacancies in the Co sites should be responsible for the occurrence of the spin glass behavior of Co 0.7 Al 2 S 4 .

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Dynamic spin fluctuations in the frustrated A -site spinel CuAl2O4

Cited by 10 publications

References 49 publications

Magnetic and structural properties of the solid solution CuAl2(1−x)Ga2xO4

Magnetic and structural properties of the solid solution CuAl2(1−x)Ga2xO4

Pressure-induced transition from Jeff=1/2 to S=1/2 states in
Cho
¹
,
Kim
²
,
Lee
³

et al. 2021
Phys. Rev. B
Self Cite

High-Pressure Synthesis, Crystal Structure, and Physical Properties of a Spinel Compound Co_0.7Al₂S₄

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Dynamic spin fluctuations in the frustrated A -site spinel CuAl2O4

Cited by 10 publications

References 49 publications

Magnetic and structural properties of the solid solution CuAl2(1−x)Ga2xO4

Magnetic and structural properties of the solid solution CuAl2(1−x)Ga2xO4

Pressure-induced transition from Jeff=1/2 to S=1/2 states in Cho1, Kim2, Lee3 et al. 2021Phys. Rev. BSelf Cite

High-Pressure Synthesis, Crystal Structure, and Physical Properties of a Spinel Compound Co0.7Al2S4

Contact Info

Product

Resources

About

Pressure-induced transition from Jeff=1/2 to S=1/2 states in
Cho
¹
,
Kim
²
,
Lee
³

et al. 2021
Phys. Rev. B
Self Cite

High-Pressure Synthesis, Crystal Structure, and Physical Properties of a Spinel Compound Co_0.7Al₂S₄