Pressure-induced ferromagnetism in the topological semimetal 
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Gati, Elena; Bud’ko, Sergey L.; Wang, Lin-Lin; Valadkhani, Adrian; Gupta, Ritu; Kuthanazhi, Brinda; Li, Xiang; Wilde, John M.; Sapkota, A.; Guguchia, Zurab; Khasanov, R.; Valentí, Roser; Canfield, Paul C.

doi:10.1103/physrevb.104.155124

Cited by 31 publications

(28 citation statements)

References 58 publications

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“…The saturated moments are close to the ideal value of 7.0 µ B for Eu 2+ ions, indicating localized magnetism. These characterizations establish that the EuCd 2 As 2 samples used in this study exhibit an A-type AFM ground state below T N ≈ 9 K at ambient pressure, similar to previous reports [26,32,36].…”

Section: Resultssupporting

confidence: 90%

“…The values of the MR in EuCd 2 As 2 are large even when compared to the colossal MR in the manganites [37][38][39], and are even more striking considering that they are achieved with relatively small fields [Table I]. The fields at which the MR saturates are µ 0 H ∼ 1.5 T for H c and µ 0 H ∼ 0.2 T for H ⊥ c, which are in excellent agreement with the saturation fields [32], and indicates that the MR is associated with polarization of the Eu 2+ moments. At higher temperatures, the resistivity in zero field is substantially reduced, whereas the resistivity under |µ 0 H| 2 T remains similar to that at 0.3 K. This leads to a weakening of the MR upon warming, originating from a decrease in the zero-field resistivity with increasing temperature.…”

Section: Colossal Magnetoresistance In the Insulating Statesupporting

confidence: 53%

“…Since A-type AFM order is present in EuCd 2 As 2 up to ∼ p c2 , as indicated by the response of the resistivity to small magnetic fields (see Fig. S2 and Section S2 in the Supplementary Materials) and previous transport and µSR measurements [32], the insulating state appears tied to the AFM order.…”

Section: Resultsmentioning

confidence: 70%

“…Since the saturation field of EuCd 2 As 2 is small [Fig. 1(d)], and further reduces with increasing pressure [32], it is straightforward to assume that the A-type AFM order of EuCd 2 As 2 can be polarized to achieve a FM state using accessible magnetic fields. If the insulating state indeed relies on the presence of A-type AFM order, it should be suppressed when the AFM state becomes fully polarized.…”

Section: Colossal Magnetoresistance In the Insulating Statementioning

confidence: 99%

“…‫؍‬ 0 H (T) of additional topological states, including magnetic Dirac fermions, axion insulator, and higher-order topological insulator, are also expected given the appropriate magnetic ground state [27]. Moreover, in addition to becoming fully polarized under modest in-plane or c-axis magnetic fields [26], a FM ground state can be stabilized by changes in the synthesis protocol [31] or applying hydrostatic pressure [32], demonstrating highly-tunable magnetism. These behaviors highlight the proximity of competing magnetic ground states in EuCd 2 As 2 , which can be harnessed to manipulate its electronic topology.…”

Section: Introductionmentioning

confidence: 99%

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Consecutive topological phase transitions and colossal magnetoresistance in a magnetic topological semimetal

Du,

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et al. 2022

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The combination of magnetic symmetries and electronic band topology provides a promising route for realizing topologically nontrivial quasiparticles, and the manipulation of magnetic structures may enable the switching between topological phases, with the potential for achieving functional physical properties. Here, we report measurements of the electrical resistivity of EuCd2As2 under pressure, which show an intriguing insulating dome at pressures between pc1 ∼ 1.0 GPa and pc2 ∼ 2.0 GPa, situated between two regimes with metallic transport. The insulating state can be fully suppressed by a small magnetic field, leading to a colossal negative magnetoresistance on the order of 10 5 %, accessible via a modest field of ∼ 0.2 T. First-principles calculations reveal that the dramatic evolution of the resistivity under pressure is due to consecutive transitions of EuCd2As2 from a magnetic topological insulator to a trivial insulator, and then to a Weyl semimetal, with the latter resulting from a pressure-induced change in the magnetic ground state. Similarly, the colossal magnetoresistance results from a field-induced polarization of the magnetic moments, transforming EuCd2As2 from a trivial insulator to a Weyl semimetal. These findings underscore weak magnetic exchange couplings and spin anisotropy as ingredients for discovering tunable magnetic topological materials with desirable functionalities.

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Section: Resultssupporting

confidence: 90%

Section: Colossal Magnetoresistance In the Insulating Statesupporting

confidence: 53%

Section: Resultsmentioning

confidence: 70%

Section: Colossal Magnetoresistance In the Insulating Statementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Consecutive topological phase transitions and colossal magnetoresistance in a magnetic topological semimetal

Du,

Yang,

Nie

et al. 2022

Preprint

View full text Add to dashboard Cite

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Thermoresistivity of Carbon Nanostructures and their Polymeric Nanocomposites

Avilés

2023

Adv Materials Inter

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Carbon nanostructures such as carbon nanotubes, graphene, and its multi‐layer derivatives exhiibit temperature‐dependent electrical conductivity. They can form percolated networks inside polymers, which render electrical conductivity to nanocomposites. Upon the formation of a percolated network, thermal energy applied to the material drives structural changes of the network, which manifest as changes in electrical conductivity. This principle is used to develop smart materials with self‐sensing temperature capabilities. This critical review covers past and present research on the electrical response to temperature (thermoresistivity) of carbon nanostructures and their polymeric nanocomposites. It covers few‐ and multi‐layer graphene, carbon nanotubes, carbon‐nanostructured arrays and fibers (yarns). The mechanisms driving the thermoresistive response of individual nanostructures, their arrays, and of their polymeric nanocomposites are addressed. The role of the nanostructured filler on the thermoresistivity of polymer nanocomposites depends on its morphology and concentration. For low filler concentrations, thermal expansion of the polymer may dominate over the inherent thermoresistivity of the filler. For high filler concentrations, or for densely packed arrays of carbon nanostructures, the inherent (quantum) thermoresistive response of the nanostructures becomes dominant. The review addresses recent progress in the field, highlights current issues, synthesizes published data, and provides outlooks and insights into future directions.

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Structure, Magnetotransport, and Theoretical Study on the Layered Antiferromagnet Topological Phase EuCd₂As₂ under High Pressure

Chen

Xia

et al. 2023

Adv Quantum Tech

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Rich nontrivial topological phases rooted in the interplay between magnetism and topology in the layered antiferromagnet EuCd2As2 have captured vast attention, especially the ideal Weyl semimetal state realized in the spin‐polarized ferromagnetic (FM) structure driven by a moderate external magnetic field. In this work, combining magnetization, magneto‐transport, and structure measurements under high pressure and first principles calculations, this study finds that the pressure can drive the in‐plane antiferromagnetic structure of EuCd2As2 across an intermediate in‐plane FM structure then into the out‐of‐plane FM structure. This study also finds butterfly‐shaped MR and anomalous Hall effect under large pressure, which may support the pressure‐driven FM state. High‐pressure angle‐dispersive X‐ray diffraction and X‐ray absorption near‐edge spectroscopy measurements exclude structure transition and/or change of Eu2+ valence state as sources for the magnetic phase transitions. Alternatively, apparently reduced axial ratio (c/a) and compressed Eu‐layer space distance should play important roles. Interestingly, the calculations unveil that the out‐of‐plane FM structure hosts only one pair of Weyl nodes around the Fermi level, suggesting that pressure can be an alternative way to realize the ideal Weyl semimetal state in EuCd2As2 and will be useful for exploring exotic topological properties in such layered magnetic topological phase with strongly competing magnetic exchanges.

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Pressure-induced ferromagnetism in the topological semimetal EuCd2As2

Cited by 31 publications

References 58 publications

Consecutive topological phase transitions and colossal magnetoresistance in a magnetic topological semimetal

Consecutive topological phase transitions and colossal magnetoresistance in a magnetic topological semimetal

Thermoresistivity of Carbon Nanostructures and their Polymeric Nanocomposites

Structure, Magnetotransport, and Theoretical Study on the Layered Antiferromagnet Topological Phase EuCd₂As₂ under High Pressure

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Pressure-induced ferromagnetism in the topological semimetal EuCd2As2

Cited by 31 publications

References 58 publications

Consecutive topological phase transitions and colossal magnetoresistance in a magnetic topological semimetal

Consecutive topological phase transitions and colossal magnetoresistance in a magnetic topological semimetal

Thermoresistivity of Carbon Nanostructures and their Polymeric Nanocomposites

Structure, Magnetotransport, and Theoretical Study on the Layered Antiferromagnet Topological Phase EuCd2As2 under High Pressure

Contact Info

Product

Resources

About

Structure, Magnetotransport, and Theoretical Study on the Layered Antiferromagnet Topological Phase EuCd₂As₂ under High Pressure