“…The contrast vanishes at the Mn rows whose magnetization directions are close to the in-plane direction (i.e., θ is close to 90°). Figure 1e shows schematics of two possible spin spiral structures that can reproduce the SP-STM image; cycloidal and helical spin spirals 16 , 18 . Although we experimentally confirmed that the rotational sense is left-handed as mentioned before 18 , there is still an experimental ambiguity about the rotational type of the spin spiral, that is, helical or cycloidal spin structure.…”
Section: Resultsmentioning
confidence: 99%
“…Figure 1e shows schematics of two possible spin spiral structures that can reproduce the SP-STM image; cycloidal and helical spin spirals 16 , 18 . Although we experimentally confirmed that the rotational sense is left-handed as mentioned before 18 , there is still an experimental ambiguity about the rotational type of the spin spiral, that is, helical or cycloidal spin structure. Figure 1 STM images with non-magnetic and magnetic tips of Mn mono- and double-layers on a W(110) substrate and their possible spin structures.…”
Section: Resultsmentioning
confidence: 99%
“…revealed the Néel-type skyrmion magnetic ground state of Fe monolayer (ML) on Ir(111) by SP-STM measurements with a double-axis vector magnet 12 . In our previous work, we conducted an SP-STM measurement on Mn ML and DL formed on W(110) with a double-axis vector magnet, and clarified the unique rotational senses of homogeneous spin-spirals 18 , indicating that the magnetic structures are driven by iDMI. The rotational types are, however, still undefined experimentally whereas the cycloidal type of spin spirals are theoretically predicted as ground states 16 , 19 .…”
Section: Introductionmentioning
confidence: 96%
“…In a case where the inversion symmetry of the system is broken, the antisymmetric exchange interaction called the Dzyaloshinskii-Moriya interaction (DMI) 1 , 2 plays a significant role and causes formation of complex chiral spin structures, such as skyrmion lattices 3 – 5 , domain walls 6 , 7 , and homogeneous spin spiral structures 8 – 10 . Since the inversion symmetry is naturally broken at interfaces, 3 d magnetic ultrathin films formed on 5 d non-magnetic heavy-elemental substrates often exhibit non-collinear chiral spin structures driven by the interfacial DMI (iDMI) 11 – 18 . In magnetic structures driven by iDMI, it is predicted that spins are rotating in the plane parallel to the propagating axis, called Néel or cycloidal rotations, with unique rotational senses (right- or left-handed).…”
Section: Introductionmentioning
confidence: 99%
“…Spin-polarized scanning tunneling microscopy (SP-STM) has been utilized for this purpose with multi-axis superconducting vector magnets 12 , 13 , 18 . Meckler et al .…”
We report on experimental verification of the rotational type of chiral spin spirals in Mn thin films on a W(110) substrate using spin-polarized scanning tunneling microscopy (SP-STM) with a double-axis superconducting vector magnet. From SP-STM images using Fe-coated W tips magnetized to the out-of-plane and [001] directions, we found that both Mn mono- and double-layers exhibit cycloidal rotation whose spins rotate in the planes normal to the propagating directions. Our results agree with the theoretical prediction based on the symmetry of the system, supporting that the magnetic structures are driven by the interfacial Dzyaloshinskii-Moriya interaction.
“…The contrast vanishes at the Mn rows whose magnetization directions are close to the in-plane direction (i.e., θ is close to 90°). Figure 1e shows schematics of two possible spin spiral structures that can reproduce the SP-STM image; cycloidal and helical spin spirals 16 , 18 . Although we experimentally confirmed that the rotational sense is left-handed as mentioned before 18 , there is still an experimental ambiguity about the rotational type of the spin spiral, that is, helical or cycloidal spin structure.…”
Section: Resultsmentioning
confidence: 99%
“…Figure 1e shows schematics of two possible spin spiral structures that can reproduce the SP-STM image; cycloidal and helical spin spirals 16 , 18 . Although we experimentally confirmed that the rotational sense is left-handed as mentioned before 18 , there is still an experimental ambiguity about the rotational type of the spin spiral, that is, helical or cycloidal spin structure. Figure 1 STM images with non-magnetic and magnetic tips of Mn mono- and double-layers on a W(110) substrate and their possible spin structures.…”
Section: Resultsmentioning
confidence: 99%
“…revealed the Néel-type skyrmion magnetic ground state of Fe monolayer (ML) on Ir(111) by SP-STM measurements with a double-axis vector magnet 12 . In our previous work, we conducted an SP-STM measurement on Mn ML and DL formed on W(110) with a double-axis vector magnet, and clarified the unique rotational senses of homogeneous spin-spirals 18 , indicating that the magnetic structures are driven by iDMI. The rotational types are, however, still undefined experimentally whereas the cycloidal type of spin spirals are theoretically predicted as ground states 16 , 19 .…”
Section: Introductionmentioning
confidence: 96%
“…In a case where the inversion symmetry of the system is broken, the antisymmetric exchange interaction called the Dzyaloshinskii-Moriya interaction (DMI) 1 , 2 plays a significant role and causes formation of complex chiral spin structures, such as skyrmion lattices 3 – 5 , domain walls 6 , 7 , and homogeneous spin spiral structures 8 – 10 . Since the inversion symmetry is naturally broken at interfaces, 3 d magnetic ultrathin films formed on 5 d non-magnetic heavy-elemental substrates often exhibit non-collinear chiral spin structures driven by the interfacial DMI (iDMI) 11 – 18 . In magnetic structures driven by iDMI, it is predicted that spins are rotating in the plane parallel to the propagating axis, called Néel or cycloidal rotations, with unique rotational senses (right- or left-handed).…”
Section: Introductionmentioning
confidence: 99%
“…Spin-polarized scanning tunneling microscopy (SP-STM) has been utilized for this purpose with multi-axis superconducting vector magnets 12 , 13 , 18 . Meckler et al .…”
We report on experimental verification of the rotational type of chiral spin spirals in Mn thin films on a W(110) substrate using spin-polarized scanning tunneling microscopy (SP-STM) with a double-axis superconducting vector magnet. From SP-STM images using Fe-coated W tips magnetized to the out-of-plane and [001] directions, we found that both Mn mono- and double-layers exhibit cycloidal rotation whose spins rotate in the planes normal to the propagating directions. Our results agree with the theoretical prediction based on the symmetry of the system, supporting that the magnetic structures are driven by the interfacial Dzyaloshinskii-Moriya interaction.
Skyrmions are topologically protected non-collinear magnetic structures. Their stability is ideally suited to carry information in, e.g., racetrack memories. The success of such a memory critically depends on the ability to stabilize and manipulate skyrmions at low magnetic fields. The non-collinear Dzyaloshinskii-Moriya interaction originating from spin-orbit coupling drives skyrmion formation. It competes with Heisenberg exchange and magnetic anisotropy favoring collinear states. Isolated skyrmions in ultra-thin films so far required magnetic fields as high as several Tesla. Here, we show that isolated skyrmions in a monolayer of Co/Ru(0001) can be stabilized down to vanishing fields. Even with the weak spin-orbit coupling of the 4d element Ru, homochiral spin spirals and isolated skyrmions were detected with spin-sensitive scanning tunneling microscopy. Density functional theory calculations explain the stability of the chiral magnetic features by the absence of magnetic anisotropy energy.
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