Evolution of Griffiths-like Anomaly in Isostructural Swedenborgite Compounds Ho<sub>1−<i>x</i></sub>Er<sub><i>x</i></sub>BaCo<sub>4</sub>O<sub>7+<i>δ</i></sub>
In this study, we investigate the presence of the Griffiths-like anomaly in the geometrically frustrated antiferromagnet <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>HoBaCo</mi><mn>...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-06-01
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| Series: | Magnetochemistry |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2312-7481/11/7/55 |
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| Summary: | In this study, we investigate the presence of the Griffiths-like anomaly in the geometrically frustrated antiferromagnet <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>HoBaCo</mi><mn>4</mn></msub></semantics></math></inline-formula><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi mathvariant="normal">O</mi><mrow><mn>7</mn><mo>+</mo><mi>δ</mi></mrow></msub></semantics></math></inline-formula> and globally its absence in <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>ErBaCo</mi><mn>4</mn></msub></semantics></math></inline-formula><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi mathvariant="normal">O</mi><mrow><mn>7</mn><mo>+</mo><mi>δ</mi></mrow></msub></semantics></math></inline-formula>, despite only small differences in the ionic radii, <i>f</i>-electron occupancy, and the corresponding crystal structures of the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>Ho</mi><mrow><mn>3</mn><mo>+</mo></mrow></msup></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>Er</mi><mrow><mn>3</mn><mo>+</mo></mrow></msup></semantics></math></inline-formula>-members. Previous studies have identified the Griffiths phase in the Dy-analog, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>DyBaCo</mi><mn>4</mn></msub></semantics></math></inline-formula><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi mathvariant="normal">O</mi><mrow><mn>7</mn><mo>+</mo><mi>δ</mi></mrow></msub></semantics></math></inline-formula>, suggesting certain inherent features of this class of materials that regularly give rise to such anomalies. To explore the curious disappearance of such an anomalous feature in <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>ErBaCo</mi><mn>4</mn></msub></semantics></math></inline-formula><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi mathvariant="normal">O</mi><mrow><mn>7</mn><mo>+</mo><mi>δ</mi></mrow></msub></semantics></math></inline-formula>, we prepared a series of compounds with varying compositions <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>Ho</mi><mrow><mn>1</mn><mo>−</mo><mi>x</mi></mrow></msub></semantics></math></inline-formula><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>Er</mi><mi>x</mi></msub></semantics></math></inline-formula><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>BaCo</mi><mn>4</mn></msub></semantics></math></inline-formula><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi mathvariant="normal">O</mi><mrow><mn>7</mn><mo>+</mo><mi>δ</mi></mrow></msub></semantics></math></inline-formula> (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0</mn><mo>≤</mo><mi>x</mi><mo>≤</mo><mn>1</mn></mrow></semantics></math></inline-formula>) and systematically studied the evolution of various physical properties as a function of Er-doping. Our experimental studies, including X-ray diffraction (XRD), magnetic, X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), heat capacity, and muon spin relaxation spectroscopy (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>μ</mi></semantics></math></inline-formula>SR spectroscopy), revealed that while the Griffiths-like anomaly indeed disappears with doping at the macroscopic level, signatures of inhomogeneity are retained in <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>ErBaCo</mi><mn>4</mn></msub></semantics></math></inline-formula><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi mathvariant="normal">O</mi><mrow><mn>7</mn><mo>+</mo><mi>δ</mi></mrow></msub></semantics></math></inline-formula> too, at least at the local level. Overall, our results highlight the significant role of ionic radius and local structural distortions in stabilizing the Griffiths phase in this class of systems. |
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| ISSN: | 2312-7481 |