1
|
Chen Z, Chen Z, Liu ZQ, Holtz ME, Li CJ, Wang XR, Lü WM, Motapothula M, Fan LS, Turcaud JA, Dedon LR, Frederick C, Xu RJ, Gao R, N'Diaye AT, Arenholz E, Mundy JA, Venkatesan T, Muller DA, Wang LW, Liu J, Martin LW. Electron Accumulation and Emergent Magnetism in LaMnO_{3}/SrTiO_{3} Heterostructures. Phys Rev Lett 2017; 119:156801. [PMID: 29077457 DOI: 10.1103/physrevlett.119.156801] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Indexed: 06/07/2023]
Abstract
Emergent phenomena at polar-nonpolar oxide interfaces have been studied intensely in pursuit of next-generation oxide electronics and spintronics. Here we report the disentanglement of critical thicknesses for electron reconstruction and the emergence of ferromagnetism in polar-mismatched LaMnO_{3}/SrTiO_{3} (001) heterostructures. Using a combination of element-specific x-ray absorption spectroscopy and dichroism, and first-principles calculations, interfacial electron accumulation, and ferromagnetism have been observed within the polar, antiferromagnetic insulator LaMnO_{3}. Our results show that the critical thickness for the onset of electron accumulation is as thin as 2 unit cells (UC), significantly thinner than the observed critical thickness for ferromagnetism of 5 UC. The absence of ferromagnetism below 5 UC is likely induced by electron overaccumulation. In turn, by controlling the doping of the LaMnO_{3}, we are able to neutralize the excessive electrons from the polar mismatch in ultrathin LaMnO_{3} films and thus enable ferromagnetism in films as thin as 3 UC, extending the limits of our ability to synthesize and tailor emergent phenomena at interfaces and demonstrating manipulation of the electronic and magnetic structures of materials at the shortest length scales.
Collapse
Affiliation(s)
- Zuhuang Chen
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Zhanghui Chen
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Z Q Liu
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - M E Holtz
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - C J Li
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
- NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore
| | - X Renshaw Wang
- School of Physical and Mathematical Sciences & School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 637371, Singapore
| | - W M Lü
- Condensed Matter Science and Technology Institute, School of Science, Harbin Institute of Technology, Harbin 150081, People's Republic of China
| | - M Motapothula
- NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore
| | - L S Fan
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - J A Turcaud
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - L R Dedon
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - C Frederick
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - R J Xu
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - R Gao
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - A T N'Diaye
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - E Arenholz
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - J A Mundy
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - T Venkatesan
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
- NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore
| | - D A Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - L-W Wang
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Jian Liu
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - L W Martin
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| |
Collapse
|
2
|
Mundy JA, Schaab J, Kumagai Y, Cano A, Stengel M, Krug IP, Gottlob DM, Dog Anay H, Holtz ME, Held R, Yan Z, Bourret E, Schneider CM, Schlom DG, Muller DA, Ramesh R, Spaldin NA, Meier D. Functional electronic inversion layers at ferroelectric domain walls. Nat Mater 2017; 16:622-627. [PMID: 28319611 DOI: 10.1038/nmat4878] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 02/06/2017] [Indexed: 06/06/2023]
Abstract
Ferroelectric domain walls hold great promise as functional two-dimensional materials because of their unusual electronic properties. Particularly intriguing are the so-called charged walls where a polarity mismatch causes local, diverging electrostatic potentials requiring charge compensation and hence a change in the electronic structure. These walls can exhibit significantly enhanced conductivity and serve as a circuit path. The development of all-domain-wall devices, however, also requires walls with controllable output to emulate electronic nano-components such as diodes and transistors. Here we demonstrate electric-field control of the electronic transport at ferroelectric domain walls. We reversibly switch from resistive to conductive behaviour at charged walls in semiconducting ErMnO3. We relate the transition to the formation-and eventual activation-of an inversion layer that acts as the channel for the charge transport. The findings provide new insight into the domain-wall physics in ferroelectrics and foreshadow the possibility to design elementary digital devices for all-domain-wall circuitry.
Collapse
Affiliation(s)
- J A Mundy
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - J Schaab
- Department of Materials, ETH Zurich, 8093 Zürich, Switzerland
| | - Y Kumagai
- Department of Materials, ETH Zurich, 8093 Zürich, Switzerland
| | - A Cano
- CNRS, Université de Bordeaux, ICMCB, UPR 9048, 33600 Pessac, France
| | - M Stengel
- ICREA-Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra, Spain
| | - I P Krug
- Institut für Optik und Atomare Physik, TU Berlin, 10623 Berlin, Germany
| | - D M Gottlob
- Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - H Dog Anay
- Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - M E Holtz
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - R Held
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA
| | - Z Yan
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Physics, ETH Zurich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
| | - E Bourret
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - C M Schneider
- Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - D G Schlom
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA
| | - D A Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA
| | - R Ramesh
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Materials Science and Engineering and Department of Physics, UC Berkeley, Berkeley, California 94720, USA
| | - N A Spaldin
- Department of Materials, ETH Zurich, 8093 Zürich, Switzerland
| | - D Meier
- Department of Materials, ETH Zurich, 8093 Zürich, Switzerland
- Department of Materials Science and Engineering, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| |
Collapse
|
3
|
Nie YF, Zhu Y, Lee CH, Kourkoutis LF, Mundy JA, Junquera J, Ghosez P, Baek DJ, Sung S, Xi XX, Shen KM, Muller DA, Schlom DG. Atomically precise interfaces from non-stoichiometric deposition. Nat Commun 2014; 5:4530. [DOI: 10.1038/ncomms5530] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 06/27/2014] [Indexed: 11/09/2022] Open
|
4
|
Quackenbush NF, Tashman JW, Mundy JA, Sallis S, Paik H, Misra R, Moyer JA, Guo JH, Fischer DA, Woicik JC, Muller DA, Schlom DG, Piper LFJ. Nature of the metal insulator transition in ultrathin epitaxial vanadium dioxide. Nano Lett 2013; 13:4857-4861. [PMID: 24000961 DOI: 10.1021/nl402716d] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We have combined hard X-ray photoelectron spectroscopy with angular dependent O K-edge and V L-edge X-ray absorption spectroscopy to study the electronic structure of metallic and insulating end point phases in 4.1 nm thick (14 units cells along the c-axis of VO2) films on TiO2(001) substrates, each displaying an abrupt MIT centered at ~300 K with width <20 K and a resistance change of ΔR/R > 10(3). The dimensions, quality of the films, and stoichiometry were confirmed by a combination of scanning transmission electron microscopy with electron energy loss spectroscopy, X-ray spectroscopy, and resistivity measurements. The measured end point phases agree with their bulk counterparts. This clearly shows that, apart from the strain induced change in transition temperature, the underlying mechanism of the MIT for technologically relevant dimensions must be the same as the bulk for this orientation.
Collapse
Affiliation(s)
- N F Quackenbush
- Department of Physics, Applied Physics and Astronomy, Binghamton University , Binghamton, New York 13902, United States
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
5
|
Du ZY, Hicks M, Spratt P, Mundy JA, Macdonald PS. Cardioprotective effects of pinacidil pretreatment and lazaroid (U74500A) preservation in isolated rat hearts after 12-hour hypothermic storage. Transplantation 1998; 66:158-63. [PMID: 9701257 DOI: 10.1097/00007890-199807270-00003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
BACKGROUND Two important processes in the preservation of the function of donor hearts are the maintenance of ATP-sensitive potassium channel activity during myocardial ischemia and the scavenging of reactive oxygen species formed during reperfusion. The aim of this study was to compare the effect of three protocols on the preservation of hemodynamic function in isolated rat hearts after hypothermic storage. These protocols were: (1) pretreatment of the heart with a potassium channel opener (200 microM pinacidil); (2) storage of the heart in an aspartate-enriched extracellular cardioplegic solution containing the lazaroid antioxidant, U74500A (30 microM); and (3) a combination of protocols 1 and 2. METHODS Hearts from Wistar rats were perfused on a Langendorff apparatus. After stabilization in working mode, baseline measurements of heart rate, coronary and aortic flow, and cardiac output were performed. Hearts (n=6 in each group) were then randomized to protocols 1-3, untreated controls, or vehicle-treated controls. Hearts were stored in extracellular-based preservation solution for 12 hr at 2-3 degrees C, remounted on the perfusion apparatus, and stabilized as before; hemodynamic measurements were then repeated. RESULTS Recovery of hemodynamic function was enhanced by pinacidil pretreatment or incorporation of lazaroid in the storage solution, but the combination of these two treatments produced the best results. CONCLUSIONS Combined pharmacological activation of ATP-sensitive potassium channels before cardioplegia and the addition of U74500A to the preservation solution is associated with significantly enhanced hemodynamic function in the isolated rat heart after 12 hr of hypothermic storage. These data suggest a novel use for these agents in the transplantation context.
Collapse
Affiliation(s)
- Z Y Du
- Division of Clinical Pharmacology and Toxicology, St. Vincent's Hospital, Darlinghurst NSW, Australia
| | | | | | | | | |
Collapse
|
6
|
|
7
|
Schyvens CG, Owe-Young RA, Spratt PM, Mundy JA, Farnsworth AE, Macdonald PS. Papaverive abolishes endothelium-dependent dilatation of human internal mammary arteries in vitro. Clin Exp Pharmacol Physiol 1997; 24:223-8. [PMID: 9131289 DOI: 10.1111/j.1440-1681.1997.tb01811.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
1. The purpose of the present study was to examine the effects of papaverine-HCl, administered into the lumen of the human internal mammary artery (IMA) during harvesting of this vessel, on vascular reactivity in vitro and to specifically test the hypothesis that intraluminal administration of papaverine-HCl impairs endothelium-dependent vasodilation. 2. The present study measured in vitro dilator and constrictor responses of terminal segments of human IMA. Internal mammary artery segments were obtained either prior to routine administration of intraluminal papaverine (pre-P) or after papaverine administration (post-P) in patients undergoing coronary artery bypass grafting. In addition, the viability of cultured human saphenous vein endothelial cells exposed to papaverine-HCl was examined. 3. Cumulative concentrations of U46619, 5-hydroxytryptamine and phenylephrine (PE) produced active contractions in post-P IMA rings. Contractile responses to low concentrations of endothelin-1 were significantly enhanced in post-PIMA compared with pre-P IMA segments. 4. Maximal endothelium-dependent vasodilator responses of pre-P IMA segments to cumulative concentrations of acetylcholine (ACh) and the calcium ionophore A23187 were 49 +/- 7 and 66 +/- 4%, respectively, of the initial active tension induced by PE (1 mumol/L). 5. Maximal endothelium-dependent vasodilator responses were markedly attenuated in post-P IMA (6 +/- 6 and 11 +/- 10% for ACh and A23187, respectively; P < 0.0001 for both vasodilators compared with pre-P). Post-P IMA relaxed completely to the endothelium-independent vasodilator sodium nitroprusside. 6. Exposure of cultured human saphenous vein endothelial cells to papaverine-HCl (1.2 and 12.0 mg/mL) for 1 h resulted in the reduced viability of these cells. 7. The loss of endothelium-dependent relaxation could dangerously predispose the IMA graft to vasospasm in the postoperative period.
Collapse
Affiliation(s)
- C G Schyvens
- Cardiopulmonary Transplant Unit, St Vincent's Hospital, Darlinghurst, New South Wales, Australia
| | | | | | | | | | | |
Collapse
|
8
|
Winlaw DS, Schyvens CG, Smythe GA, Du ZY, Rainer SP, Keogh AM, Mundy JA, Lord RS, Spratt PM, MacDonald PS. Urinary nitrate excretion is a noninvasive indicator of acute cardiac allograft rejection and nitric oxide production in the rat. Transplantation 1994; 58:1031-6. [PMID: 7974731 DOI: 10.1097/00007890-199411150-00010] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Cytokine induction of calcium-independent nitric oxide synthase is associated with production of large amounts of nitric oxide (NO). NO is a free radical that is rapidly degraded to nitrite and nitrate. Measurement of plasma and urinary nitrate is an indirect marker of NO production and previous studies have demonstrated that plasma nitrate rises with allograft rejection. The purpose of this study was to examine the temporal relationship between the rise in urinary nitrate excretion and the onset of graft rejection, and to determine the effect of conventional immunosuppression on nitrate excretion. The heterotropic model of cardiac transplantation in the rat was used, with Brown-Norway to Lewis allografts and Lewis to Lewis isograft controls. Twenty-four-hour urine specimens were collected before and after transplantation. Urinary nitrate excretion was measured by gas chromatography/mass spectrometry. Each group was treated with (1) no immunosuppression, (2) dexamethasone (3 mg/kg), or (3) CsA (10 mg/kg) on days 0, 1, and 2. Time to rejection for untreated allografts was 5.1 +/- 0.1 days, extending to 8.4 +/- 0.5 and 9.6 +/- 0.4 days with dexamethasone and CsA treatment, respectively. There was a significant rise in nitrate excretion on days 4, 7, and 9 for control, dexamethasone-treated, and CsA-treated allografts, respectively, preceding evidence of rejection. Untreated allograft rejection was associated with a peak in nitrate excretion 8 times that of basal excretion by isografts. Treatment of the allografts with dexamethasone and CsA significantly attenuated peak nitrate excretion compared with untreated allografts with a only a 2- to 3-fold rise preceding rejection. Results indicate that allograft rejection is associated with a dramatic increase in peak urinary nitrate excretion that is attenuated by standard immunosuppressive therapy. An increase in nitrate excretion precedes evidence of graft rejection, and may serve as a noninvasive marker of graft rejection.
Collapse
Affiliation(s)
- D S Winlaw
- Department of Cardiopulmonary Transplantation, St. Vincent's Hospital, Sydney, Australia
| | | | | | | | | | | | | | | | | | | |
Collapse
|