Submillimeter EPR of Co:Rb2MgF4 and anomalous g-values

Motokawa, M.; Ohta, H.; Maki, Naoki

doi:10.1007/bf01009889

Cited by 160 publications

(36 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1 and the obtained g-value is 2:14 AE 0:01, which is consistent with the g-value of 2.16 obtained from the analysis of the magnetic susceptibility by Okamoto et al Figure 3 shows the temperature dependence of ESR spectra observed at 315 GHz. As we used different cryostats and detectors above 86 K and below 86 K, 19,20) the signal to noise ratio is different. It is clear that the resonance field shifts to lower field and the broadening of absorption line occurs at low temperature.…”

mentioning

confidence: 99%

See 1 more Smart Citation

High-Field ESR Measurements of S=1/2 Kagome Lattice Antiferromagnet BaCu₃V₂O₈(OH)₂

et al. 2010

Self Cite

View full text Add to dashboard Cite

High-field electron spin resonance (ESR) measurements have been performed on vesignieite BaCu 3 V 2 O 8 (OH) 2 , which is considered as a nearly ideal model substance of S ¼ 1=2 kagome antiferromagnet, in the temperature region from 1.9 to 265 K. The frequency region is from 60 to 360 GHz and the applied pulsed magnetic field is up to 16 T. Observed g-value and linewidth show the increase below 20 K, which suggest the development of the short range order. Moreover, a gapless spin liquid ground state is suggested from the frequency-field relation at 1.9 K.KEYWORDS: high-field ESR, kagome lattice, frustration, vesignieite, spin dynamics DOI: 10.1143/JPSJ.79.023708Highly frustrated magnetism has attracted much attention recently. Especially S ¼ 1=2 kagome lattice antiferromagnet (KAFM) is very important because it is considered to have stronger geometrical frustration than the well studied triangular lattice antiferromagnet. 1) Therefore, the ground state of S ¼ 1=2 KAFM has attracted much interest, but the theoretical studies about its ground state are still controversial. The exact diagonalization studies suggest a nonmagnetic spin liquid state with a small spin gap of the order of J=20, where J is the nearest-neighbor exchange interaction. 2)On the other hand, the other numerical calculation studies suggest the gapless ground state.3) Therefore, the experimental studies using the model substance of S ¼ 1=2 KAFM are really required, but a few model substances are known at present.Suggested model substances of S ¼ 1=2 KAFM at present are Cu 2þ minerals, herbertsmithite ZnCu 3 (OH) 6 Cl 2 , 4) vol-6) Herbertsmithite has a rhombohedral structure with the space group R " 3 3m, and is named ''structurally perfect kagome compound'' 4) because of the ideal kagome geometry of Cu 2þ ions. Although the strong antiferromagnetic exchange interaction is expected in herbertsmithite from the large negative Weiss temperature ¼ À300 K, 7) no long range order is observed down to 50 mK from the specific heat measurement 8) suggesting the existence of strong frustration in the system. However, the neutron diffraction measurement suggested that about 10% of the Cu 2þ sites in the kagome plane are substituted by Zn 2þ ions, 9) which is also supported by the NMR measurement.10)The divergent magnetic susceptibility toward T ¼ 0 observed in herbertsmithite 4) may be related to the existence of the impurity spins caused by these substitutions. On the other hand, no such substitution of Cu 2þ sites in the kagome plane is expected in the model substance volborthite because a mutual exchange between Cu 2þ and V 5þ ions is unfavorable in terms of the ionic radius and the Madelung energy. The existence of the strong frustration is suggested because the magnetic susceptibility shows no long range order down to 60 mK, but exhibits a tiny spin glass transition at 1.1 K in spite of the large negative Weiss temperature ¼ À115 K. 11,12) The magnetic susceptibility shows a broad maximum at 21 K and it shows a gapless behavior suggested by a large fin...

show abstract

mentioning

confidence: 99%

“…Observed temperature region is from 1.9 to 265 K. The details of our high field ESR system can be found in refs. 15,19,20. A polycrystalline sample of BaCu 3 V 2 O 8 (OH) 2 (vesignieite) was prepared by the hydrothermal method.…”

mentioning

confidence: 99%

High-Field ESR Measurements of S=1/2 Kagome Lattice Antiferromagnet BaCu₃V₂O₈(OH)₂

et al. 2010

Self Cite

View full text Add to dashboard Cite

show abstract

“…The details of our high field ESR system can be found in refs. [15][16][17][18]. Since the synthesis of a single crystal is very difficult, we used the natural single crystal mineral azurite (Cu 3 (CO 3 ) 2 (OH) 2 ) for the measurements.…”

mentioning

confidence: 99%

High Field ESR Study of theS=1/2 Diamond-Chain Substance Cu₃(CO₃)₂(OH)₂up to the Magnetization Plateau Region

et al. 2003

Self Cite

View full text Add to dashboard Cite

High field ESR measurements of Cu 3 (CO 3 ) 2 (OH) 2 have been performed in the frequency region from 50 to 900 GHz and in the temperature region from 1.8 to 265 K using the pulsed magnetic field up to 36 T. The large g-shifts below 23 K and the characteristic temperature dependence of the linewidth are discussed in connection with the two maxima of magnetic susceptibility observed at 5 and 23 K. Our ESR results together with the magnetization and theoretical results suggest that the ground state of the system is in the spin fluid (SF) phase at low field and low temperature. From the frequency-field dependence measurements at 1.8 K, the direct transition, which is closely related to the magnetization plateau from 16 to 26 T at 1.5 K, is observed for the first time. The observed frequency-field diagram suggests that the exchange interaction in the dimer is estimated to be about 50 K (1057 GHz). Recently, the study of quantum spin systems with competing interactions, that is, frustration and quantum fluctuation, has attracted great interest. The diamond chain system, as shown in Fig. 1(a), is one of such systems, and it has attracted much theoretical interest, particularly after the suggestion by Ishii et al. that Cu 3 Cl 6 (H 2 O) 2 Á2H 8 C 4 SO 2 may be the model substance for the S ¼ 1=2 distorted diamond chain with the spin gap.1) Takano et al. studied the S ¼ 1=2 diamond chain model in the case of J 1 ¼ J 3 , and showed that the ground state is in the ferrimagnetic (FRI), tetramer-dimer (TD) and dimer-monomer (DM) phases for J 2 =J 1 < 0:909, 0:909 < J 2 =J 1 < 2 and 2 < J 2 =J 1 , respectively.2) It was extended to the S ¼ 1=2 distorted diamond chain model with J 1 , J 2 and J 3 , as shown in Fig. 1(a) by Okamoto et al. and Tonegawa et al., and the ground state phase diagram in the case of H ¼ 0, composed of ferrimagnetic (FRI), dimerized (D) and spin fluid (SF) phases as schematically shown in Fig. 1(b), were determined.3,4) It turned out that the TD and DM states were special cases of the twofold degenerate D and SF states, respectively. Tonegawa et al. also studied the magnetization curve numerically. 4,5) However, it turned out recently that the compound assumed to be Cu 3 Cl 6 -(H 2 O) 2 Á2H 8 C 4 SO 2 was actually Cu 2 Cl 4 Á2H 8 C 4 SO 2 which can be described by the S ¼ 1=2 double-spin chain model. 6)Therefore, the model substance for the S ¼ 1=2 distorted diamond chain is desired strongly from the experimental point of view.Recently, Kikuchi et al. proposed that Cu 3 (CO 3 ) 2 (OH) 2 might be the first model substance for the S ¼ 1=2 diamond chain. 7) Cu 3 (CO 3 ) 2 (OH) 2 is a well-known natural mineral azurite, which has a dark blue color, and it often contains the natural mineral malachite Cu 2 (OH) 2 (CO 3 ), which has a light green color. However, little was known about the magnetic properties of Cu 3 (CO 3 ) 2 (OH) 2 previously, except for the antiferromagnetic order at T N ¼ 1:9 K from the NMR and magnetic susceptibility measurements 8,9) in the restricted low-temperature region between 1.55...

show abstract

“…High-field and high-frequency ESR measurement is one of the major trends in the ESR spectroscopy recently, because it has several advantages as compared with conventional X-band (~10 GHz) ESR system [1][2][3][4][5][6][7]. The advantages are high resolution of the g-value, observation of a broad line, observation of resonance with a large zerofield splitting, and so on.…”

Section: Introductionmentioning

confidence: 99%

Development of High-Field ESR System Using SQUID Magnetometer and its Application to Measurement under High Pressure

Sakurai¹,

Fujimoto²,

Okubo³

et al. 2013

Journal of Magnetics

View full text Add to dashboard Cite

We have developed a high-field and high-frequency ESR system using a commercially available magnetometer equipped with the superconducting quantum interference device (SQUID). This is magnetization detection type ESR and ESR is observed as a change of the magnetization at the resonance condition under irradiation of the electromagnetic wave. The frequency range is from 70 to 315 GHz and the maximum magnetic field is 5 T. The sensitivity is estimated to be 10 13 spins/G. The advantage of this system is that the high-field ESR measurements can be made very easily and quantitatively. Moreover, this high-field ESR can be applied to the measurements under pressure by using a widely used piston-cylinder pressure cell.

show abstract

Submillimeter EPR of Co:Rb2MgF4 and anomalous g-values

Cited by 160 publications

References 1 publication

High-Field ESR Measurements of S=1/2 Kagome Lattice Antiferromagnet BaCu₃V₂O₈(OH)₂

High-Field ESR Measurements of S=1/2 Kagome Lattice Antiferromagnet BaCu₃V₂O₈(OH)₂

High Field ESR Study of theS=1/2 Diamond-Chain Substance Cu₃(CO₃)₂(OH)₂up to the Magnetization Plateau Region

Development of High-Field ESR System Using SQUID Magnetometer and its Application to Measurement under High Pressure

Contact Info

Product

Resources

About

Submillimeter EPR of Co:Rb2MgF4 and anomalous g-values

Cited by 160 publications

References 1 publication

High-Field ESR Measurements of S=1/2 Kagome Lattice Antiferromagnet BaCu3V2O8(OH)2

High-Field ESR Measurements of S=1/2 Kagome Lattice Antiferromagnet BaCu3V2O8(OH)2

High Field ESR Study of theS=1/2 Diamond-Chain Substance Cu3(CO3)2(OH)2up to the Magnetization Plateau Region

Development of High-Field ESR System Using SQUID Magnetometer and its Application to Measurement under High Pressure

Contact Info

Product

Resources

About

High-Field ESR Measurements of S=1/2 Kagome Lattice Antiferromagnet BaCu₃V₂O₈(OH)₂

High-Field ESR Measurements of S=1/2 Kagome Lattice Antiferromagnet BaCu₃V₂O₈(OH)₂

High Field ESR Study of theS=1/2 Diamond-Chain Substance Cu₃(CO₃)₂(OH)₂up to the Magnetization Plateau Region