Pressure control of magnetic clusters in strongly inhomogeneous ferromagnetic chalcopyrites

Djabrailov²,

2019

Sci Rep

There are the chains of transition-metal cations alternating with the anions of oxygen in ternary transition-metal oxides. When a p-orbital of the oxygen connects the half-filled and empty d-orbitals of adjacent transition-metal cations, double-exchange ferromagnetism takes place. Although double exchange has been well explored, the nature of novel criticality, induced by it, is yet not uncovered. We explored the magnetic-field scaling in the heat capacity of a Sm0.55Sr0.45MnO3 manganite, one of the best ternary transition-metal oxides as it is completely ferromagnetic, and found novel criticality - unordinary critical exponents which are the consequence of coherence of Coulomb lattice distortion and ferromagnetism. The coherence is caused by the trinity of the mass, the charge and the spin of an electron. When the d and p orbitals overlaps, it quickly walks from one site to the another due its lightest mass. And due to its electric charge, it equalizes the valences of the transition-metal cations in the chains and so diminishes the Coulomb lattice distortion. At last, its spin forces magnetic moments of transition-metal cations to ferromagnetically arrange. The disappearance of Coulomb distortions widens the overlap and lowers the elastic lattice energy, so that not only the spin of an electron, but also its electric charge strengthens ferromagnetism. That nonlinear effect strengthens the critical behaviour and critical exponents come off any known universality classes. Thus, the symbiotic coherence of annihilating Coulomb distortions and arising ferromagnetism is a reason of the novel criticality.

Section: Discussionmentioning

confidence: 90%

Nature of novel criticality in ternary transition-metal oxides

Djabrailov²,

2019

Sci Rep

J. Phys. D: Appl. Phys.

“…It is established that structural transformation in a chalcopyrite lattice is responsible for both types of magnetization hysteresis and causes a remarkable structure-driven MR effect where magnetotransport features depend on the magnetic nature of the compositions. Trying to explain an unusual behavior of hysteresis, we believe that this effect can possibly be attributed to strong interacting clusters and their volume properties [12] in a new high-pressure phase. A deeper understanding of the interplay between the host lattice distortion and MnAs clusters remains to be elucidated in future.…”

Section: Resultsmentioning

confidence: 99%

“…The family of Mn-doped II-IV-V 2 semiconductors have attracted considerable attention both experimentally [5][6][7] and theoretically [8,9] due to room-temperature (RT) ferromagnetism which holds potential in the modern concept of spin devices. Although the scientific interest devoted to these materials is smaller than that of III-V diluted magnetic semiconductors (DMS) [10], interest in these compounds has been resurrected due to the unusual properties of their magnetic inhomogeneities such as recent demonstrations of metamagnetic-like behavior under pressure, as well as the path to pressure controlled response of magnetic clusters at RT [11,12]. Mn-doped ZnGeAs 2 is the most representative due to its high Curie temperature T C ≈ 367 K [13].…”

Section: Introductionmentioning

confidence: 99%

Changes in the magnetization hysteresis direction and structure-driven magnetoresistance of a chalcopyrite-based magnetic semiconductor

Arslanov

Kilański

López-Moreno

et al. 2016

An unusual change in the hysteresis direction is believed as rare phenomenon associated with perovskite-type structure. Such 'anomalous' magnetization hysteresis could possess a direct impact on the giant magnetoresistance (MR). Here we demonstrate that the room-temperature magnetization versus pressure for chalcopyrite semiconductor Zn 1−x Mn x GeAs 2 with x = 0.01 follows a usual direction of hysteresis, while the direction turns into anomalous for x = 0.07. Both these phenomena are results of a pressure-induced structural transition occurring in the host material, as is evident from volumetric measurements and ab initio calculations. This structural transition gives rise to the pressure-enhanced large MR and changes it drastically. Unlike the case of x = 0.01 where MR can be well reproduced within a theoretical approach, the presence of magnetic inhomogeneities for x = 0.07 induces an unexpected crossover from large positive to non-saturating negative MR (~92% at H = 5 kOe) in the new high-pressure phase. These results suggest that Zn 1−x Mn x GeAs 2 provides an example of a chalcopyrite-based material whose functional possibilities could be expanded through a new type of 'structuredriven' MR.

“…In the spin or memory devices, reversing magnetization through powerful, fast, and tunable techniques is very important in writing process. , This control and tuning of magnetization of the system can be achieved by switching one magnetic state to another through various external sources like magnetic field, laser field, , temperature, pressure, ,− and spin-polarized current. − However, these approaches for magnetism manipulations are not efficient as they act nonlocally, which can affect the neighboring units. Thus, the search for alternative and efficient techniques through which magnetism can be controlled and manipulated at nanoscale brought significant attention toward the application of an external electric field (EEF).…”

Section: Introductionmentioning

confidence: 99%

Electric Field Control of Magnetism of a Mn Dimer Supported on a Carbon-Doped h-BN Surface

Sahoo¹,

Nayak²,

Pradhan

2022

J. Phys. Chem. C

Using density functional theory, we show that the interaction between two Mn atoms can be tuned from the antiferromagnetic (AFM) to the ferromagnetic (FM) state by creating charge disproportion between the two on a 2D surface. The nonmetallic planar heterostructure, the 2D surface, in our work is designed by doping carbon hexagon rings in a hexagonal boron nitride (h-BN) sheet. In addition, we show that an external electric field can be used to control the charge disproportion and hence the magnetism. In fact, our calculations demonstrate that the magnetic states of the dimer can be switched from AFM to FM, or vice versa, in an external electric field. The origin of this magnetic switching is explained by using the charge transfer from (or to) the Mn dimer to (or from) the 2D material. The switching between antiferromagnetic to ferromagnetic states can be useful for future spintronics applications.