Quantification of local Ising magnetism in rare-earth pyrogermanates Er2Ge2O7 and Yb2Ge2O7

Pajerowski, Daniel M.; Taddei, Keith M.; Sanjeewa, Liurukara D.; Savici, Andrei T.; Stone, Matthew B.; Kolis, Joseph W.

doi:10.1103/PhysRevB.101.014420

Title: Quantification of local Ising magnetism in rare-earth pyrogermanates ${Er}_{2} {Ge}_{2} O_{7}$ and ${Yb}_{2} {Ge}_{2} O_{7}$

Abstract

Recently, a local-Ising-type magnetic order was inferred from neutron diffraction of the antiferromagnetic Er₂Ge₂O₇ (pg-ErGO) with an applied magnetic field. Here, we use neutron spectroscopy to investigate the energetics of pg-ErGO and the isostructural Yb₂Ge₂O₇ (pg-YbGO) to evaluate the adequacy of the local-Ising description. To begin, we generate a model of the magnetic structure of pg-YbGO using neutron diffraction and find a net ferromagnetic moment. While pg-ErGO and pg-YbGO have highly symmetric crystal structures (P4₁2₁2 tetragonal space group 92) with only one trivalent rare-earth magnetic site, the point symmetry of the rare-earth site is low with only a single symmetry element (point group C₁). For both compounds, the energy scale of the first excited state is large compared to the magnetic ordering temperature, suggesting Ising character. The ground-state Kramer's doublet of both compounds is dominated by the maximal m_J component. However, the low point group symmetry of the rare-earth site leads to finite mixing of all other m_J's, which suggests potential deviations from Ising behavior. Moreover, quasielastic scattering is observed deep in the ordered state of pg-ErGO and pg-YbGO that may be due to non-Ising behavior. The dominant magnetic interaction in both compounds is found to be magnetostatic by consideringmore »« less

Authors:

^[1];

^[1]; Sanjeewa, Liurukara D. ^[2];

^[1];

^[1]; Kolis, Joseph W. ^[3]

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Clemson Univ., SC (United States)
Clemson Univ., SC (United States)

Publication Date:: Wed Jan 15 00:00:00 EST 2020

Research Org.:: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:: 1606915

Grant/Contract Number:: AC05-00OR22725

Resource Type:: Accepted Manuscript

Journal Name:: Physical Review B

Additional Journal Information:: Journal Volume: 101; Journal Issue: 1; Journal ID: ISSN 2469-9950

Publisher:: American Physical Society (APS)

Country of Publication:: United States

Language:: English

Subject:: 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats


                    Pajerowski, Daniel M., Taddei, Keith M., Sanjeewa, Liurukara D., Savici, Andrei T., Stone, Matthew B., and Kolis, Joseph W. Quantification of local Ising magnetism in rare-earth pyrogermanates Er2Ge2O7 and Yb2Ge2O7.  United States: N. p., 2020. 
Web.  doi:10.1103/PhysRevB.101.014420.

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                    Pajerowski, Daniel M., Taddei, Keith M., Sanjeewa, Liurukara D., Savici, Andrei T., Stone, Matthew B., & Kolis, Joseph W. Quantification of local Ising magnetism in rare-earth pyrogermanates Er2Ge2O7 and Yb2Ge2O7.  United States.  https://doi.org/10.1103/PhysRevB.101.014420

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                    Pajerowski, Daniel M., Taddei, Keith M., Sanjeewa, Liurukara D., Savici, Andrei T., Stone, Matthew B., and Kolis, Joseph W. Wed .  
"Quantification of local Ising magnetism in rare-earth pyrogermanates Er2Ge2O7 and Yb2Ge2O7".  United States.  https://doi.org/10.1103/PhysRevB.101.014420.  https://www.osti.gov/servlets/purl/1606915.

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@article{osti_1606915,

  title        = {Quantification of local Ising magnetism in rare-earth pyrogermanates Er2Ge2O7 and Yb2Ge2O7},

  author       = {Pajerowski, Daniel M. and Taddei, Keith M. and Sanjeewa, Liurukara D. and Savici, Andrei T. and Stone, Matthew B. and Kolis, Joseph W.},

  abstractNote = {Recently, a local-Ising-type magnetic order was inferred from neutron diffraction of the antiferromagnetic Er2Ge2O7 (pg-ErGO) with an applied magnetic field. Here, we use neutron spectroscopy to investigate the energetics of pg-ErGO and the isostructural Yb2Ge2O7 (pg-YbGO) to evaluate the adequacy of the local-Ising description. To begin, we generate a model of the magnetic structure of pg-YbGO using neutron diffraction and find a net ferromagnetic moment. While pg-ErGO and pg-YbGO have highly symmetric crystal structures (P41212 tetragonal space group 92) with only one trivalent rare-earth magnetic site, the point symmetry of the rare-earth site is low with only a single symmetry element (point group C1). For both compounds, the energy scale of the first excited state is large compared to the magnetic ordering temperature, suggesting Ising character. The ground-state Kramer's doublet of both compounds is dominated by the maximal mJ component. However, the low point group symmetry of the rare-earth site leads to finite mixing of all other mJ's, which suggests potential deviations from Ising behavior. Moreover, quasielastic scattering is observed deep in the ordered state of pg-ErGO and pg-YbGO that may be due to non-Ising behavior. The dominant magnetic interaction in both compounds is found to be magnetostatic by considering the magnetic excitations in the ordered state. Lastly, from consideration of these data, the pg-YbGO is more Ising-like than pg-ErGO. Also, quantum multicritical points are anticipated with applied magnetic field in both compounds.},

  doi          = {10.1103/PhysRevB.101.014420},

  journal      = {Physical Review B},

  number       = 1,

  volume       = 101,

  place        = {United States},

  year         = {Wed Jan 15 00:00:00 EST 2020},

  month        = {Wed Jan 15 00:00:00 EST 2020}

}

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Works referenced in this record:

Local-Ising-type magnetic order and metamagnetism in the rare-earth pyrogermanate ${Er}_{2} {Ge}_{2} O_{7}$
journal, January 2019

Taddei, K. M.; Sanjeewa, L.; Kolis, J. W.
Physical Review Materials, Vol. 3, Issue 1
DOI: 10.1103/PhysRevMaterials.3.014405

Mantid—Data analysis and visualization package for neutron scattering and $μ$ SR experiments
journal, November 2014

Arnold, O.; Bilheux, J. C.; Borreguero, J. M.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 764
DOI: 10.1016/j.nima.2014.07.029

The crystal structure of the ethyl sulphates of the rare earthes and yttrium
journal, August 1937

Ketelaar, J. A. A.
Physica, Vol. 4, Issue 8
DOI: 10.1016/S0031-8914(37)80158-5

Magnetic pyrochlore oxides
journal, January 2010

Gardner, Jason S.; Gingras, Michel J. P.; Greedan, John E.
Reviews of Modern Physics, Vol. 82, Issue 1
DOI: 10.1103/RevModPhys.82.53

Measurements of the magnetic susceptibility and anisotropy of Tb2Ge2O7 single crystal
journal, February 2000

Jana, Y. M.; Ghosh, M.; Ghosh, D.
Journal of Magnetism and Magnetic Materials, Vol. 210, Issue 1-3
DOI: 10.1016/S0304-8853(99)00759-3

Crystallographic data for solvated rare earth chlorides
journal, December 1966

Graeber, E. J.; Conrad, G. H.; Duliere, S. F.
Acta Crystallographica, Vol. 21, Issue 6
DOI: 10.1107/S0365110X66004420

Measurements of magnetic susceptibilities and anisotropy of erbium pyrogermanate (Er2Ge2O7) crystal
journal, May 1998

Ghosh, M.; Jana, S.; Ghosh, D.
Solid State Communications, Vol. 107, Issue 3
DOI: 10.1016/S0038-1098(98)00161-6

Er Mössbauer study of Er2Ge2O7
journal, September 2003

Cadogan, J. M.; Ryan, D. H.; Stewart, G. A.
Journal of Magnetism and Magnetic Materials, Vol. 265, Issue 2
DOI: 10.1016/S0304-8853(03)00265-8

Role of the electrostatic model in calculating rare-earth crystal-field parameters
journal, July 1998

Edvardsson, Sverker; Klintenberg, Mattias
Journal of Alloys and Compounds, Vol. 275-277
DOI: 10.1016/S0925-8388(98)00309-0

Parametric analysis of the energy levels of Er3+ ions in hydrated erbium chloride ErCl3·6H2O and in frozen dilute aqueous solutions of erbium chloride
journal, April 1984

Couture, L.; Rajnak, K.
Chemical Physics, Vol. 85, Issue 2
DOI: 10.1016/0301-0104(84)85042-9

Recent advances in magnetic structure determination by neutron powder diffraction
journal, October 1993

Rodríguez-Carvajal, Juan
Physica B: Condensed Matter, Vol. 192, Issue 1-2
DOI: 10.1016/0921-4526(93)90108-I

Magnetothermodynamics of the Ising antiferromagnet ${Dy}_{2} {Ge}_{2} O_{7}$
journal, September 2008

Ke, X.; Dahlberg, M. L.; Morosan, E.
Physical Review B, Vol. 78, Issue 10
DOI: 10.1103/PhysRevB.78.104411

Magnetochemistry
book, January 1986

Carlin, Richard L.
Springer Berlin, Heidelberg
DOI: 10.1007/978-3-642-70733-9

The thermal and magnetic properties of ytterbium ethyl sulphate between 20°k and 1°k
journal, July 1957

Cooke, A. H.; Mckim, F. R.; Meyer, H.
Philosophical Magazine, Vol. 2, Issue 19
DOI: 10.1080/14786435708242731

Dipolar magnetic order in the rare earth ethyl sulfates
journal, January 1990

Xu, Jingchun; Roser, M. R.; Corruccini, L. R.
Journal of Low Temperature Physics, Vol. 78, Issue 1-2
DOI: 10.1007/BF00682106

Lead palladium titanate: A room temperature nanoscale multiferroic thin film
journal, February 2020

Mishra, K. K.; Instan, Alvaro A.; Kumari, Shalini
Scientific Reports, Vol. 10, Issue 1
DOI: 10.1038/s41598-020-59961-w

Magnetic Properties of Rare Earth Metals
book, January 1972

Elliott, R. J.
DOI: 10.1007/978-1-4757-5691-3

VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data
journal, October 2011

Momma, Koichi; Izumi, Fujio
Journal of Applied Crystallography, Vol. 44, Issue 6
DOI: 10.1107/S0021889811038970

Flux growth of the rare earth germanates
journal, May 1973

Wanklyn, Barbara M.
Journal of Materials Science, Vol. 8, Issue 5
DOI: 10.1007/BF00561220

Metamagnetism
journal, September 1977

Stryjewski, E.; Giordano, N.
Advances in Physics, Vol. 26, Issue 5
DOI: 10.1080/00018737700101433

A new protocol for the determination of magnetic structures using simulated annealing and representational analysis (SARAh)
journal, March 2000

Wills, A. S.
Physica B: Condensed Matter, Vol. 276-278
DOI: 10.1016/S0921-4526(99)01722-6

Caloric and magnetic study of five rare-earth ionic compounds having predominantly magnetic dipole-dipole interaction
journal, September 1972

Lagendijk, E.; Blöte, H. W. J.; Huiskamp, W. J.
Physica, Vol. 61, Issue 2
DOI: 10.1016/0031-8914(72)90069-9

Caloric and magnetic properties of two compounds having predominantly magnetic dipole-dipole interactions: DyCl3·6H2O and ErCl3·6H2O
journal, April 1973

Lagendijk, E.; Huiskamp, W. J.
Physica, Vol. 65, Issue 1
DOI: 10.1016/0031-8914(73)90238-3

Universal Quantum Simulators
journal, August 1996

Lloyd, S.
Science, Vol. 273, Issue 5278
DOI: 10.1126/science.273.5278.1073

Thermal Study of Crystal Field Splittings in Erbium Ethylsulfate
journal, December 1962

Gerstein, B. C.; Penney, C. J.; Spedding, F. H.
The Journal of Chemical Physics, Vol. 37, Issue 11
DOI: 10.1063/1.1733062

History of the Lenz-Ising Model
journal, October 1967

Brush, Stephen G.
Reviews of Modern Physics, Vol. 39, Issue 4
DOI: 10.1103/RevModPhys.39.883

Optical absorption spectra and crystal field parameters of dysprosium and erbium Germanates
journal, April 1977

Wardzyńska, M.; Wanklyn, B. M.
Physica Status Solidi (a), Vol. 40, Issue 2
DOI: 10.1002/pssa.2210400234

Structure and magnetic properties of the ${Ho}_{2} {Ge}_{2} O_{7}$ pyrogermanate
journal, June 2008

Morosan, E.; Fleitman, J. A.; Huang, Q.
Physical Review B, Vol. 77, Issue 22
DOI: 10.1103/PhysRevB.77.224423

Crystal-field splitting in dysprosium ethyl sulphate-an infrared and theoretical investigation
journal, December 1984

Dawber, P. G.; Finn, C. B. P.; Jamshidi, H.
Journal of Physics C: Solid State Physics, Vol. 17, Issue 36
DOI: 10.1088/0022-3719/17/36/026

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Title: Quantification of local Ising magnetism in rare-earth pyrogermanates Er 2 Ge 2 O 7 and Yb 2 Ge 2 O 7

Abstract

Citation Formats

Local-Ising-type magnetic order and metamagnetism in the rare-earth pyrogermanate Er 2 Ge 2 O 7 journal, January 2019

Mantid—Data analysis and visualization package for neutron scattering and μ SR experiments journal, November 2014

The crystal structure of the ethyl sulphates of the rare earthes and yttrium journal, August 1937

Magnetic pyrochlore oxides journal, January 2010

Measurements of the magnetic susceptibility and anisotropy of Tb2Ge2O7 single crystal journal, February 2000

Crystallographic data for solvated rare earth chlorides journal, December 1966

Measurements of magnetic susceptibilities and anisotropy of erbium pyrogermanate (Er2Ge2O7) crystal journal, May 1998

Er Mössbauer study of Er2Ge2O7 journal, September 2003

Role of the electrostatic model in calculating rare-earth crystal-field parameters journal, July 1998

Parametric analysis of the energy levels of Er3+ ions in hydrated erbium chloride ErCl3·6H2O and in frozen dilute aqueous solutions of erbium chloride journal, April 1984

Recent advances in magnetic structure determination by neutron powder diffraction journal, October 1993

Magnetothermodynamics of the Ising antiferromagnet Dy 2 Ge 2 O 7 journal, September 2008

Magnetochemistry book, January 1986

The thermal and magnetic properties of ytterbium ethyl sulphate between 20°k and 1°k journal, July 1957

Dipolar magnetic order in the rare earth ethyl sulfates journal, January 1990

Lead palladium titanate: A room temperature nanoscale multiferroic thin film journal, February 2020

Magnetic Properties of Rare Earth Metals book, January 1972

VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data journal, October 2011

Flux growth of the rare earth germanates journal, May 1973

Metamagnetism journal, September 1977

A new protocol for the determination of magnetic structures using simulated annealing and representational analysis (SARAh) journal, March 2000

Caloric and magnetic study of five rare-earth ionic compounds having predominantly magnetic dipole-dipole interaction journal, September 1972

Caloric and magnetic properties of two compounds having predominantly magnetic dipole-dipole interactions: DyCl3·6H2O and ErCl3·6H2O journal, April 1973

Universal Quantum Simulators journal, August 1996

Thermal Study of Crystal Field Splittings in Erbium Ethylsulfate journal, December 1962

History of the Lenz-Ising Model journal, October 1967

Optical absorption spectra and crystal field parameters of dysprosium and erbium Germanates journal, April 1977

Structure and magnetic properties of the Ho 2 Ge 2 O 7 pyrogermanate journal, June 2008

Crystal-field splitting in dysprosium ethyl sulphate-an infrared and theoretical investigation journal, December 1984

Title: Quantification of local Ising magnetism in rare-earth pyrogermanates ${Er}_{2} {Ge}_{2} O_{7}$ and ${Yb}_{2} {Ge}_{2} O_{7}$

Local-Ising-type magnetic order and metamagnetism in the rare-earth pyrogermanate ${Er}_{2} {Ge}_{2} O_{7}$
journal, January 2019

Mantid—Data analysis and visualization package for neutron scattering and $μ$ SR experiments
journal, November 2014

The crystal structure of the ethyl sulphates of the rare earthes and yttrium
journal, August 1937

Magnetic pyrochlore oxides
journal, January 2010

Measurements of the magnetic susceptibility and anisotropy of Tb2Ge2O7 single crystal
journal, February 2000

Crystallographic data for solvated rare earth chlorides
journal, December 1966

Measurements of magnetic susceptibilities and anisotropy of erbium pyrogermanate (Er2Ge2O7) crystal
journal, May 1998

Er Mössbauer study of Er2Ge2O7
journal, September 2003

Role of the electrostatic model in calculating rare-earth crystal-field parameters
journal, July 1998

Parametric analysis of the energy levels of Er3+ ions in hydrated erbium chloride ErCl3·6H2O and in frozen dilute aqueous solutions of erbium chloride
journal, April 1984

Recent advances in magnetic structure determination by neutron powder diffraction
journal, October 1993

Magnetothermodynamics of the Ising antiferromagnet ${Dy}_{2} {Ge}_{2} O_{7}$
journal, September 2008

Magnetochemistry
book, January 1986

The thermal and magnetic properties of ytterbium ethyl sulphate between 20°k and 1°k
journal, July 1957

Dipolar magnetic order in the rare earth ethyl sulfates
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Lead palladium titanate: A room temperature nanoscale multiferroic thin film
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Magnetic Properties of Rare Earth Metals
book, January 1972

VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data
journal, October 2011

Flux growth of the rare earth germanates
journal, May 1973

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journal, September 1977

A new protocol for the determination of magnetic structures using simulated annealing and representational analysis (SARAh)
journal, March 2000

Caloric and magnetic study of five rare-earth ionic compounds having predominantly magnetic dipole-dipole interaction
journal, September 1972

Caloric and magnetic properties of two compounds having predominantly magnetic dipole-dipole interactions: DyCl3·6H2O and ErCl3·6H2O
journal, April 1973

Universal Quantum Simulators
journal, August 1996

Thermal Study of Crystal Field Splittings in Erbium Ethylsulfate
journal, December 1962

History of the Lenz-Ising Model
journal, October 1967

Optical absorption spectra and crystal field parameters of dysprosium and erbium Germanates
journal, April 1977

Structure and magnetic properties of the ${Ho}_{2} {Ge}_{2} O_{7}$ pyrogermanate
journal, June 2008

Crystal-field splitting in dysprosium ethyl sulphate-an infrared and theoretical investigation
journal, December 1984