Tag Archives: FM-KPFM

Multi-Channel Exploration of O Adatom on TiO2(110) Surface by Scanning Probe Microscopy

In the article “Multi-Channel Exploration of O Adatom on TiO2(110) Surface by Scanning Probe Microscopy” Huan Fei Wen, Yasuhiro Sugawara and Yan Jun describe how they studied the O2 dissociated state under the different O2 exposed temperatures with atomic resolution by scanning probe microscopy (SPM) and imaged the O adatom by simultaneous atomic force microscopy (AFM)/scanning tunneling microscopy (STM).*

The effect of AFM operation mode on O adatom contrast was investigated, and the interaction of O adatom and the subsurface defect was observed by AFM/STM. Multi-channel exploration was performed to investigate the charge transfer between the adsorbed O and the TiO2(110) by obtaining the frequency shift, tunneling current and local contact potential difference at an atomic scale. The tunneling current image showed the difference of the tunneling possibility on the single O adatom and paired O adatoms, and the local contact potential difference distribution of the O-TiO2(110) surface institutively revealed the charge transfer from TiO2(110) surface to O adatom. The experimental results are expected to be helpful in investigating surface/interface properties by SPM. *

Iridium-coated ultrastiff AFM cantilever SD-T10L100 from the NANOSENSORS Special Developments List (typical Force constant 2 000 N/m) were used in the presented study.

The cantilever tip was first degassed at approximately 650 K for 30 min and then cleaned by Ar ion bombardment to remove the contaminants, prior to the measurements. Features of the surface structure were related to the charge states of the tip apex, and a stable tip was essential to accurately characterize the surface structure and properties in the experiment. The imaging mode became stable in AFM experiments when the metal-coated Si cantilever was employed in the experiments. *

Figure 5. from “Multiple images of TiO2(110) surface with atomic resolution and corresponding line profiles” by Huan Fei Wen et al. - Iridium coated NANOSENSORS SD-T10L100 AFM probes were used
(a) Frequency shift (∆f) image, (b) tunneling current (<It>) image and (c) local contact potential difference (VLCPD) image. (d,e) The line profiles along the blue line on the surface in (b,c). (f0 = 805 kHz, Q = 27623, ∆f = −260 Hz, VDC = 1.3 V, VAC = 1.5 V, A = 500 pm, size: 3.5 × 3.2 nm2). Multiple images of TiO2(110) surface with atomic resolution and corresponding line profiles. (a) Frequency shift (∆f) image, (b) tunneling current (<It>) image and (c) local contact potential difference (VLCPD) image. (d,e) The line profiles along the blue line on the surface in (b,c). (f0 = 805 kHz, Q = 27623, ∆f = −260 Hz, VDC = 1.3 V, VAC = 1.5 V, A = 500 pm, size: 3.5 × 3.2 nm2).

Figure 5. from “Multiple images of TiO2(110) surface with atomic resolution and corresponding line profiles” by Huan Fei Wen et al.
(a) Frequency shift (∆f) image, (b) tunneling current (<It>) image and (c) local contact potential difference (VLCPD) image. (d,e) The line profiles along the blue line on the surface in (b,c). (f0 = 805 kHz, Q = 27623, ∆f = −260 Hz, VDC = 1.3 V, VAC = 1.5 V, A = 500 pm, size: 3.5 × 3.2 nm2). Multiple images of TiO2(110) surface with atomic resolution and corresponding line profiles. (a) Frequency shift (∆f) image, (b) tunneling current (<It>) image and (c) local contact potential difference (VLCPD) image. (d,e) The line profiles along the blue line on the surface in (b,c). (f0 = 805 kHz, Q = 27623, ∆f = −260 Hz, VDC = 1.3 V, VAC = 1.5 V, A = 500 pm, size: 3.5 × 3.2 nm2).

*Huan Fei Wen, Yasuhiro Sugawara and Yan Jun
Multi-Channel Exploration of O Adatom on TiO2(110) Surface by Scanning Probe Microscopy
Nanomaterials 2020, 10(8), 1506
DOI: https://doi.org/10.3390/nano10081506

Please follow this external link to read the full article: https://www.mdpi.com/2079-4991/10/8/1506/htm

More articles mentioning the use of NANOSENSORS ultrastiff AFM probes:

Yuuki Adachi, Huan Fei Wen, Quanzhen Zhang, Masato Miyazaki, Yasuhiro Sugawara and Yan Jun Li
Elucidating the charge state of an Au nanocluster on the oxidized/reduced rutile TiO2 (110) surface using non-contact atomic force microscopy and Kelvin probe force microscopy
Nanoscale Adv., 2020, 2, 2371-2375 (Paper)
DOI: 10.1039/C9NA00776H
https://pubs.rsc.org/en/content/articlehtml/2020/na/c9na00776h

Huan Fei Wen, Hongqian Sang Yasuhiro Sugawara, and Yan Jun Li
Dynamic behavior of OH and its atomic contrast with O adatom on the Ti site of TiO2(110) at 78 K by atomic force microscopy imaging
Appl. Phys. Lett. 117, 051602 (2020)
DOI: https://doi.org/10.1063/5.0016657

Yuuki Adachi, Yasuhiro Sugawara, and Yan Jun Li
Remotely Controlling the Charge State of Oxygen Adatoms on a Rutile TiO2(110) Surface Using Atomic Force Microscopy
J. Phys. Chem. C 2020, 124, 22, 12010–12015
DOI: https://doi.org/10.1021/acs.jpcc.0c03117

Huan Fei Wen, Quanzhen Zhang, Yuuki Adachi, Masato Miyazaki, Yasuhiro Sugawara, Yan JunLi
Contrast inversion of O adatom on rutile TiO2(1 1 0)-(1 × 1) surface by atomic force microscopy imaging
Applied Surface Science Volume 505, 1 March 2020, 144623
DOI: https://doi.org/10.1016/j.apsusc.2019.144623

Open Access The article “Multi-Channel Exploration of O Adatom on TiO2(110) Surface by Scanning Probe Microscopy” by Huan Fei Wen, Yasuhiro Sugawara and Yan Jun is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

Macroscopic manifestation of domain-wall magnetism and magnetoelectric effect in a Néel-type skyrmion host

In the article “Macroscopic manifestation of domain-wall magnetism and magnetoelectric effect in a Néel-type skyrmion host” Korbinian Geirhos, Boris Gross, Bertalan G. Szigeti, Andrea Mehlin, Simon Philipp, Jonathan S. White, Robert Cubitt, Sebastian Widmann, Somnath Ghara, Peter Lunkenheimer, Vladimir Tsurkan, Erik Neuber, Dmytro Ivaneyko, Peter Milde, Lukas M. Eng, Andrey O. Leonov, Sándor Bordács, Martino Poggio and István Kézsmárki report a magnetic state in GaV4Se8 which emerges exclusively in samples with mesoscale polar domains and not in polar mono-domain crystals.*

It is manifested by a sharp anomaly in the magnetic susceptibility and the magnetic torque, distinct from other anomalies observed also in polar mono-domain samples upon transitions between the cycloidal, the Néel-type skyrmion lattice and the ferromagnetic states. *

The authors ascribe this additional transition to the transformation of distinct magnetic textures, confined to polar domain walls (DW), to the ferromagnetic (FM) state. The emergence of these DW-confined magnetic states is likely driven by the mismatch of different spin spirals, hosted by the adjacent domains. A clear anomaly in the magneto-current indicates that the DW-confined magnetic states also have strong contributions to the magnetoelectric response. *

The authors expect polar DWs to commonly host such confined magnetic edge states and, thus, offer a fertile ground to explore novel forms of magnetism. *

To characterize the polar domains and to estimate the density of DWs in GaV4Se8, K. Geirhos et al. combined several complementary scanning probe microscopy techniques, including non-contact atomic force microscopy ( nc-AFM ), scanning dissipation microscopy ( SDM ), and frequency-modulated Kelvin-probe force microscopy ( KPFM ). *

In attempt to observe spin cycloidal and Néel-type skyrmion textures within polar domains of GaV4Se8, only evidenced by small-angle neutron scattering measurements so far43, the authors of the article also carried out magnetic force microscopy (MFM) measurements. A second purpose of the MFM study was to explore possible magnetic states confined to the vicinity of DWs, as reported in GaV4S8. *

NANOSENSORS™ SSS-QMFMR high resolution magnetic AFM probes for ultra high vacuum conditions were used for the magnetic measurements with scanning probe microscopy. *

NANOSENSORS™ conductive wear-resistant Platinum Silicide AFM probes of the PtSi-FM type were used for all other measurements described in the article. *

Supplementary Figure 1 a – d from “Macroscopic manifestation of domain-wall magnetism and magnetoelectric effect in a Néel-type skyrmion host” by K. Geirhos et al:

Typical ferroelectric do-main pattern observed on the (001) cleaved GaV4Se8 crystal surface  atT=10  K.
a, The topography is characterized by stripes roughly parallel to the [110] axis and folds parallel to the [010]  axis. The latter originate in the differently oriented distortion of the ferroelastic domains. The color scale corresponds to the z-displacement of the tip.
b ,In the dissipation channel of the nc-AFM every second domain appears bright. For the non-magnetic tip the dissipation originates from electric interactions. The dissipated power is indicated by the color scale. Please have a look at the full article to view the full supplementary figure.
NANOSENSORS Platinum Silicide PtSi-FM AFM probes were used for the imaging.
Supplementary Figure 1 a – d from “Macroscopic manifestation of domain-wall magnetism and magnetoelectric effect in a Néel-type skyrmion host” by K. Geirhos et al:

Typical ferroelectric do-main pattern observed on the (001) cleaved GaV4Se8 crystal surface  atT=10  K.
a, The topography is characterized by stripes roughly parallel to the [110] axis and folds parallel to the [010]  axis. The latter originate in the differently oriented distortion of the ferroelastic domains. The color scale corresponds to the z-displacement of the tip.
b ,In the dissipation channel of the nc-AFM every second domain appears bright. For the non-magnetic tip the dissipation originates from electric interactions. The dissipated power is indicated by the color scale. Please have a look at the full article to view the full supplementary figure.

*Korbinian Geirhos, Boris Gross, Bertalan G. Szigeti, Andrea Mehlin, Simon Philipp, Jonathan S. White, Robert Cubitt, Sebastian Widmann, Somnath Ghara, Peter Lunkenheimer, Vladimir Tsurkan, Erik Neuber, Dmytro Ivaneyko, Peter Milde, Lukas M. Eng, Andrey O. Leonov, Sándor Bordács, Martino Poggio and István Kézsmárki
Macroscopic manifestation of domain-wall magnetism and magnetoelectric effect in a Néel-type skyrmion host
npj Quantum Materials volume 5, Article number: 44 (2020)
DOI: https://doi.org/10.1038/s41535-020-0247-z

Please follow this external link to read the full article: https://rdcu.be/b7lgW

Open Access The article “Macroscopic manifestation of domain-wall magnetism and magnetoelectric effect in a Néel-type skyrmion host” by Korbinian Geirhos, Boris Gross, Bertalan G. Szigeti, Andrea Mehlin, Simon Philipp, Jonathan S. White, Robert Cubitt, Sebastian Widmann, Somnath Ghara, Peter Lunkenheimer, Vladimir Tsurkan, Erik Neuber, Dmytro Ivaneyko, Peter Milde, Lukas M. Eng, Andrey O. Leonov, Sándor Bordács, Martino Poggio and István Kézsmárki is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

Kelvin probe force microscopy work function characterization of transition metal oxide crystals under ongoing reduction and oxidation

Controlling the work function of transition metal oxides is of key importance with regard to future energy production and storage. As the majority of applications involve the use of heterostructures, the most suitable characterization technique is Kelvin probe force microscopy (KPFM), which provides excellent energetic and lateral resolution.*

In their study “Kelvin probe force microscopy work function characterization of transition metal oxide crystals under ongoing reduction and oxidation» Dominik Wrana, Karol Cieślik, Wojciech Belza, Christian Rodenbücher, Krzysztof Szot and Franciszek Krok present the advantages and limitations of the FM-KPFM technique using the example of a newly discovered TiO/SrTiO3(100) (metal/insulator) heterostructure, which has potentially high technological relevance.*

In the same article a combined conductivity and work function study from the same surface area is presented, showing the possibility of obtaining full information on the electronic properties when the KPFM technique is accompanied by local conductivity atomic force microscopy (LC-AFM).*

The authos present the measurement of the crystalline TiO work function and its dependence on the gaseous pressure of air using Kelvin probe force microscopy.

In order to ensure reproducible FM-KPFM results, two different types of AFM cantilevers were used: NANOSENSORS™ PointProbe® Plus PPP-ContPt (PtIr-coated) and NANOSENSORS™ Platinum Silicide PtSi-FM.*

Such cantilevers are widely used as conducting tips in a contact mode AFM, allowing for a high lateral resolution in conductivity measurements. The remarkable mechanical stability of the selected cantilevers allowed for the noncontact mode measurements (with a Kelvin loop) using the very same tip, maintaining oscillations at the higher harmonics of the fundamental frequency (≈75 kHz). Hence, in order to record current and CPD maps from the very same sample area, KPFM measurements were first performed with the soft cantilever forced to oscillate at higher harmonics, then the tip was retracted tens of nanometers from the surface, all feedback loops were turned down and a contact mode AFM scan was performed when approached with a single loop maintaining a deflection set point of 10–30 mV. The high conductivity of both TiO and STO materials enabled a low sample bias of +1 mV for the LC-AFM measurements to be used.*

Figure 4 from “Kelvin probe force microscopy work function characterization of transition metal oxide crystals under ongoing reduction and oxidation”: KPFM lateral resolution on high TiO/STO structures. a) Topography and b) work function of TiO nanowire array on SrTiO3(100). c) Height (black line) and work function (green line) profiles of two adjacent TiO nanowires, showing high KPFM contrast. d) Dependence of the CPD resolution (estimated as ΔCPD/CPD, see c) on the separation between TiO nanowires, with A + B/X asymptote fit. Insets show the SEM images of the actual PtSi cantilever used in the experiments with a tip radius of 15 nm.

*Dominik Wrana, Karol Cieślik, Wojciech Belza, Christian Rodenbücher, Krzysztof Szot, Franciszek Krok
Kelvin probe force microscopy work function characterization of transition metal oxide crystals under ongoing reduction and oxidation
Beilstein Journal of Nanotechnology 2019, 10, 1596–1607
DOI: 10.3762/bjnano.10.155

Please follow this external link to read the full article: https://www.beilstein-journals.org/bjnano/articles/10/155

Open Access The article “Kelvin probe force microscopy work function characterization of transition metal oxide crystals under ongoing reduction and oxidation” by Dominik Wrana, Karol Cieślik, Wojciech Belza, Christian Rodenbücher, Krzysztof Szot and Franciszek Krok is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.