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- Title
Polaron freezing and the quantum liquid-crystal phase in the ferromagnetic metallic La<sub>0.67</sub>Ca<sub>0.33</sub>MnO<sub>3</sub>.
- Authors
Panopoulos, Nikolaos; Pissas, Michael; Kim, Hae Jin; Kim, Jin-Gyu; Yoo, Seung Jo; Hassan, Jamal; AlWahedi, Yasser; Alhassan, Saeed; Fardis, Michael; Boukos, Nikos; Papavassiliou, Georgios
- Abstract
The remarkable electronic properties of colossal magnetoresistive manganites are widely believed to be caused by the competition between a ferromagnetic metallic state and an antiferromagnetic insulating state with complex spin, charge, and orbital ordering. However, the physics underlying their magnetotransport properties is still not clear, especially the role of correlated Jahn–Teller polarons, which depending on temperature and doping, might form a liquid, glass or stripe polaron state. This question touches one of the most fundamental problems in the physics of doped Mott insulators, i.e. understanding the mechanism that chemical doping makes an insulator becoming superconductive as in the case of cuprates, or exhibiting the colossal magnetoresistance effect, as in the case of manganites. Here, by using 139La NMR and high resolution transmission electron microscopy in the temperature range 3.2–1000 K, we have monitored the formation and evolution of CE-type polarons in optimally doped La0.67Ca0.33MnO3. While NMR experiments show that correlated polarons dominate electron spin dynamics in the ferromagnetic phase, at very low temperatures they appear to form a quantum liquid-crystal like ferromagnetic phase, embedded into a ferromagnetic matrix with 3D polaron correlations. This is evidence that similarly to high Tc cuprates, quantum soft phases underlie the exotic physical properties of colossal magnetoresistive manganites. Manganites: Polarons freeze into a quantum spin liquid crystal phase A detailed investigation reveals the role of polarons in manganites, which are known for their colossal magnetoresistance. Polarons are quasiparticles formed from charged carriers and the lattice distortions they induce when immersed into an ionic environment. A team of researchers from Greece, Korea and UAE have now studied the properties of the archetypal manganite La0.67Ca0.33MnO3 in a wide temperature range (3.2–1000 K). They observe the formation of polarons in the paramagnetic phase at temperatures lower than 550 K that persist even after the crossover to the ferromagnetic phase (267 K). At even lower temperatures however, they report the formation of an electron spin liquid crystal-like phase, coexisting with the initial ferromagnetic one, which becomes the dominant phase by further decreasing temperature. This confirms previous theoretical predictions for the family of doped Mott insulators and strongly suggests that there are many similarities regarding the intriguing role of polarons in the physics of manganites and superconducting cuprates, as well as between the onset of colossal magnetoresistance and superconductivity, respectively.
- Subjects
MAGNETORESISTIVE devices; FERROMAGNETIC materials; LANTHANUM compounds; POLARONS; QUANTUM liquids; LIQUID crystals
- Publication
NPJ Quantum Materials, 2018, Vol 3, Issue 1, pN.PAG
- ISSN
2397-4648
- Publication type
Article
- DOI
10.1038/s41535-018-0093-4