Noncollinear magnetism in manganese nanostructures

Zelený, Michal; Šob, Mojmı́r; Häfner, J.

doi:10.1103/physrevb.80.144414

Cited by 39 publications

(39 citation statements)

References 76 publications

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“…6(c) we show that J Mn−Mn , between Mn atoms separated by the same interatomic distance a, decreases very fast with N Mn . For freestanding 58,59 and supporting Mn nanostructures on nonmagnetic substrates, 43,58,60,61 a sensitive dependence of the exchange interaction in Mn nanostrucutures on their environment has also been verified. of Mn neighbors increases, the Mn-Mn coupling switches to AFM, and the Mn-Fe coupling between nearest neighbors changes to FM, with some competition between interactions with further neighbors taking place.…”

Section: B Mn Nanostructures On Fe(001)mentioning

confidence: 95%

First-principles studies of complex magnetism in Mn nanostructures on the Fe(001) surface

et al. 2012

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The magnetic properties of Mn nanostructures on the Fe(001) surface have been studied using the noncollinear first-principles real space-linear muffin-tin orbital-atomic sphere approximation method within density-functional theory. We have considered a variety of nanostructures such as adsorbed wires, pyramids, and flat and intermixed clusters of sizes varying from two to nine atoms. Our calculations of interatomic exchange interactions reveal the long-range nature of exchange interactions between Mn-Mn and Mn-Fe atoms. We have found that the strong dependence of these interactions on the local environment, the magnetic frustration, and the effect of spin-orbit coupling lead to the possibility of realizing complex noncollinear magnetic structures such as helical spin spiral and half-skyrmion.

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Section: B Mn Nanostructures On Fe(001)mentioning

confidence: 95%

First-principles studies of complex magnetism in Mn nanostructures on the Fe(001) surface

et al. 2012

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“…Indeed, the appearance of a spin-spiral energy minimum has been recently demonstrated by ab initio calculations for free-standing chains as well as more complex structures of Mn atoms. 27,29 In our work, we investigate how the noncollinear magnetism in Mn chains evolves upon stretching the chain and alloying with strongly AFM Cr and FM Fe, 21 alloys that are known to exist in bulk α-Mn (see, e.g., Ref. 46).…”

Section: Mn Chainsmentioning

confidence: 99%

“…While the exchange interactions have been explored intensively for finite TM magnetic clusters, both freestanding and deposited on surfaces, 9,17-20 the work for infinite monatomic TM chains concentrated almost exclusively on collinear magnetic solutions. 10,[21][22][23][24][25][26] The occurrence of noncollinear magnetic states and analysis of exchange interaction beyond the first neighbor in freestanding and deposited monatomic chains has come into the focus of interest only recently, [27][28][29] while a conclusive evidence for a spin-spiral ground state, or more complicated spin textures, The E and q axes have been added for one curve for clarity (lower right corner of right graph). In that particular case, the global energy minimum is at the end; that is, for q = 0.5 and the AFM state is most favorable.…”

Section: Introductionmentioning

confidence: 99%

“…Due to the special position of Mn chains at the borderline between competing FM and AFM exchange interactions, we anticipate the possibility of a spin-spiral ground state in the vicinity of this transition point, where J 1 is small, and long-ranged indirect exchange interactions become of importance. 34 Indeed, a whole set of noncollinear solutions has been recently predicted to occur in single-strand as well as thicker infinite and finite freestanding wires of Mn atoms, 27,29 revealing a sensitive dependence of the exchange interactions on the details of the surroundings, observed also for small deposited Mn clusters. 18 Also in two dimensions the tendency of Mn to noncollinear spin ordering is well-established.…”

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confidence: 99%

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Noncollinear magnetism in freestanding and supported monatomic Mn chains

Schubert¹,

Mokrousov

Ferriani

et al. 2011

Phys. Rev. B

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Using first-principles calculations, we study the occurrence of noncollinear magnetic order in monatomic Mn chains. First, we focus on freestanding Mn chains and demonstrate that they exhibit a pronounced noncollinear ground state in a large range of interatomic distances between atoms in the chain. By artificially varying the atomic number of Mn we investigate how the magnetic ground state is influenced by alloying the Mn chains with Fe and Cr. With increasing number of 3d electrons we find a smooth transition in the magnetic phase space starting from an antiferromagnetic state for pure Cr chains through a regime of noncollinear ground states for Mn-rich chains to a ferromagnetic solution approaching the limit of pure Fe chains. Second, we investigate the magnetism in supported Mn chains on the (110) surfaces of Cu, Pd, and Ag. We show that even a weak chain-surface hybridization is sufficient to dramatically change the magnetic coupling in the chain. Nevertheless, while we observe that Mn chains are antiferromagnetic on Pd(110), a weak noncollinear magnetic order survives for Mn chains on Cu(110) and Ag(110) a few meV in energy below the antiferromagnetic solution. We explain the sensitive dependence of the exchange interaction in Mn chains on the interatomic distance, chemical composition, and their environment based on the competition between the ferromagnetic double exchange and the antiferromagnetic kinetic exchange mechanism. Finally, we perform simulations which predict that the noncollinear magnetic order of Mn chains on Cu(110) and Ag(110) could be experimentally verified by spin-polarized scanning tunneling microscopy.

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“…43 In the vicinity of this crossover point, the Mn spins favor noncollinear magnetic order. [44][45][46] To demonstrate a strong tendency of Mn spin moments to AFM coupling at smaller values of d Mn-Mn , we plot the energy difference between the P↑↑ and P↓↑ states in Fig. 2(a).…”

Section: B Collinear Magnetic States Of the Junction From Tunneling mentioning

confidence: 99%

Conductance fingerprints of noncollinear magnetic states in single-atom contacts: A first-principles Wannier-functions study

et al. 2012

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We present a first-principles computational scheme for investigating the ballistic transport properties of onedimensional nanostructures with noncollinear magnetic order. The electronic structure is obtained within density functional theory as implemented in the full-potential linearized augmented plane-wave method and mapped to a tight-binding-like transport Hamiltonian via noncollinear Wannier functions. The conductance is then computed based on the Landauer formula using the Green's function method. As a first application, we study the conductance between two ferromagnetic Co monowires terminated by single Mn apex atoms as a function of Mn-Mn separation. We vary the Mn-Mn separation from the contact (about 2.5 to 5Å) to the far tunneling regime (5 to 10Å). The magnetization direction of the Co electrodes is chosen either in parallel or antiparallel alignment and we allow for different spin configurations of the two Mn spins. In the tunneling and into the contact regime, the conductance is dominated by s-d z 2 states. In the close contact regime (below 3.5Å), there is an additional contribution for a parallel magnetization alignment from the d xz and d yz states which give rise to an increase of the magnetoresistance as it is absent for antiparallel magnetization. If we allow the Mn spins to relax, a noncollinear spin state is formed close to contact due to the competition of ferromagnetic coupling between Mn and Co and antiferromagnetic coupling between the Mn spins. We demonstrate that the transition from a collinear to such a noncollinear spin structure as the two Mn atoms approach leaves a characteristic dip in the distance-dependent conductance and magnetoresistance of the junction. We explain this modification of the spin-valve effect due to the noncollinear spin state based on the spin-dependent hybridization between the d xz,yz states of the Mn spins and their coupling to the Co electrodes.

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Noncollinear magnetism in manganese nanostructures

Cited by 39 publications

References 76 publications

First-principles studies of complex magnetism in Mn nanostructures on the Fe(001) surface

First-principles studies of complex magnetism in Mn nanostructures on the Fe(001) surface

Noncollinear magnetism in freestanding and supported monatomic Mn chains

Conductance fingerprints of noncollinear magnetic states in single-atom contacts: A first-principles Wannier-functions study

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