Overview / Publications

good day for the UHV sputtering chamber (see base pressure)


Our research is on magnetic thin films and heterostructures.  Modern ultrahigh vacuum deposition techniques have made it possible to create 'heterostructures,' ultrathin films (dozens of atoms thick, or thinner) of one material stacked upon another; composition can be controlled routinely to the level of ~three atomic layers, with the potential for control of single monolayers.  Heterostructures of ferromagnets with other sorts of materials (metals, insulators, semiconductors) offer entirely new functional properties due to the presence of the interface, going far beyond a simple averaging of the two components.  

A canonical example of a new property engineered in a heterostructure is giant magnetoresistance (GMR) in ferromagnet/noble metal heterostructures, topic of the 2008 Nobel Prize in Physics for Albert Fert and Peter Gruenberg.  (I have slides from a short presentation of the work involved in the prize, prepared for a general audience, here  (pdf).)  The key idea is that the spin of the electrons which carry charge in a conductor can be controlled through the magnetization.  This property had direct application as a magnetic field sensor in magnetic recording heads; GMR went from first laboratory discovery (1988) to incorporation as a 'spin valve' in mass produced magnetic recording heads (1998) in just 10 years, something of a record in applied science.

Many new spin-transport-related phenomena have been discovered in the intervening years, with spin torque transfer (and magnetic random access memory, MRAM) devices serving as a focal point.  A relatively new direction for these studies, and one which has interested my group particularly in the past several years, is the possibility of controlling the flow of 'pure' spin currents (without charge, or electrical currents) in ferromagnetic heterostructures.  

The particular specialty of our lab is on high-speed / high-frequency magnetization dynamics in sheet-level films.  We have developed some unique tools in magnetic materials deposition (UHV sputtering; see picture of chamber above) to optimize dynamical properties, and ferromagnetic resonance (FMR) characterization of films in some novel configurations, in our labs at Columbia.  In collaboration with other groups, we have extended FMR to synchrotron pump-probe measurements, which allows us to probe the dynamics of different constituents of heterostructures at GHz frequencies.

The work done in our group is primarily experimental, with quantitative models (usually phenomenological) often used to interpret phenomena in better-developed materials systems.  The research area offers opportunities to work in materials development, fundamental science, and applications in magnetic information storage.

William Bailey

Book Chapter 

Magnetization dynamics

W.E. Bailey

chapter 4 in Introduction to Magnetic Random Access Memories, IEEE Press, R.B. Goldfarb, B. Dieny, and K.-J. Lee, eds. (2017) (pdf, as submitted to eds) (pdf) (e-book) 

Refereed Journal Articles


Coherent spin pumping in a strongly coupled magnon-magnon hybrid system

Yi Li, Wei Cao, Vivek P. Amin, Zhizhi Zhang, Jonathan Gibbons, Joseph Sklenar, John Pearson, Paul M. Haney, Mark D. Stiles, William E. Bailey, Valentine Novosad, Axel Hoffmann, Wei Zhang

Physical Review Letters, in production



Measurement of spin mixing conductance in Ni81Fe19/α-W and Ni81Fe19/β-W heterostructures via ferromagnetic resonance

Wei Cao, J. Liu, A. Zangiabadi, K. Barmak, W.E. Bailey 

Journal of Applied Physics 126 043902 (2019)

(pdf) (journal)

Nearly isotropic spin-pumping related Gilbert damping in Pt/Ni81Fe19 /Pt

Wei Cao, L. Yang, S. Auffret, W.E. Bailey 

Physical Review B (Condensed Matter) 99 094406 (2019)

(pdf) (journal) (cond-mat)


Characterization of spin relaxation anisotropy in Co using spin pumping

Yi Li, Wei Cao, W.E. Bailey 

Physical Review B (Condensed Matter) 94 174439 (2016)

(pdf) (journal) (cond-mat)

Phase-resolved imaging of edge-mode spin waves using scanning transmission x-ray microscopy

Cheng Cheng, Wei Cao, W.E. Bailey

Journal of Magnetism and Magnetic Materials 
(pdf) (journal) (cond-mat) 

Spin-pumping damping and magnetic proximity effect in Pd and Pt spin sink layers

M. Caminale, A. Ghosh, S. Auffret, U. Ebels, K. Ollefs, F. Wilhelm, A. Rogalev, W.E. Bailey

*Editors' suggestion (link)

Physical Review B (Condensed Matter) 94 014414 (2016) (pdf) (journal) (cond-mat)

Large spin pumping effect in antisymmetric precession of Ni79Fe21/ Ru/ Ni79Fe21

H. Yang, Y. LiW.E. Bailey

Applied Physics Letters 108 242404 (2016) (pdf) (journal) (cond-mat)

Wavenumber-dependent Gilbert damping in metallic ferromagnets

Yi Li, W.E. Bailey

Physical Review Letters116 117602 (2016)  (pdf)  (journal)  (cond-mat)

Static and dynamic magnetization of alloy gradient nanowire

Haozhe Yang, Yi Li, Min Zheng, Wei Cao, W.E. Bailey, and Ronghai Yu

Scientific Reports6 20427 (2016)  (journal) 


Inertial terms to magnetization dynamics in ferromagnetic thin films

Y. Li, A.-L. Barra, S. Auffret, U. Ebels, and W.E. Bailey

Physical Review B (Rapid Communications) 92 140413(R) (2015) (pdf) (journal)

Direct observation of symmetry-specific precession in a ferrimagnet

P. Warnicke, E. Stavitski, J.-S. Lee, A. Yang, Z. Chen, X. Zuo, S. Zohar, W.E. Bailey, V. G. Harris, and D. A. Arena 

Physical Review B (Condensed Matter) 92 104402 (2015) (pdf) (journal)


Penetration depth and absorption mechanisms of spin currents in Ir20Mn80 and Fe50Mn50 polycrystalline films by ferromagnetic resonance and spin pumping

P. Merodio, A. Ghosh, C. Lemonias, E. Gautier, U. Ebels, M. Chshiev, H. Béa, V. Baltz, W.E. Bailey
Applied Physics Letters 104 032406 (2014) (pdf) (journal)


High-efficiency GHz frequency doubling without power threshold in thin-film Ni81Fe19

C. Cheng, W.E. Bailey
Applied Physics Letters, 103 (25) 242402 (2013)(pdf) (cond-mat) (journal)

Detection of microwave phase variation in nanometer-scale magnetic heterostructures

W.E. Bailey, C. Cheng, R. Knut, O. Karis, S. Auffret, S. Zohar, D. Keavney, P. Warnicke, J-.S. Lee, D.A. Arena
Nature Communications, 4 2025 (2013) (pdf) (journal)

Measurement of transport spin polarization in FeV using point-contact Andreev reflection
M. Osofsky, L. Cheng, W.E. Bailey, K. Bussmann, D. Parker

Applied Physics Letters
, 102 212412 (2013)
(pdf) (journal)

Single-domain shape anisotropy in near-macroscopic Ni80Fe20 thin-film rectangles

Y. Li, Y. Lu, W.E. Bailey
Journal of Applied Physics, 113 17B506 (2013) (pdf) (journal) (cond-mat)

Exploring the accessible frequency range of phase-resolved ferromagnetic resonance detected with x-rays

P. Warnicke, R. Knut, E. Wahlstrom, O. Karis, W.E. Bailey, D.A. Arena
Journal of Applied Physics, 113 033904 (2013) (pdf) (journal)

Optimization of ultrasoft CoZrTa/SiO2/CoZrTa trilayer elements for integrated inductor structures

C. Cheng, R. Davies, N. Sturcken, K. Shepard, W.E. Bailey
Journal of Applied Physics, 113 17A343 (2013) (pdf)(journal)

Coupled inductors with crossed-anisotropy CoZrTa/SiO2 multilayer cores

R. Davies, N. Sturcken, C. Cheng, W.E. Bailey, K. Shepard
IEEE Transactions on Magnetics, 49 7 4009 (2013) (pdf) (journal)


Penetration depth of transverse spin current in ultrathin ferromagnets

A. Ghosh, S. Auffret, U. Ebels, W.E. Bailey

Physical Review Letters, 109 127202 (2012)  (pdf)  (journal)

Pd magnetism induced by indirect interlayer exchange coupling

W.E. BaileyA. Ghosh, S. Auffret, E. Gautier, U. Ebels, F. Wilhelm, A. Rogalev
Physical Review B (Condensed Matter), 86 144403 (2012) (pdf) (journal) (cond-mat)

Sub-micron mapping of Ghz magnetic susceptibility using scanning transmission x-ray microscopy

C. Cheng and W.E. Bailey
Applied Physics Letters101 182407 (2012) (500 Mhz AVI) (2 Ghz AVI) (pdf)  (journal)

Vector control of induced magnetic anisotropy using an in-situ quadrupole electromagnet in ultra-high vacuum sputtering

C. Cheng, N. Sturcken, K. Shepard, W.E. Bailey

Review of Scientific Instruments, 83 063903 (2012) (pdf)  (journal)

Stochastic limits in synchronous imaging of submicron magnetization dynamics using scanning transmission x-ray microscopy

C. Cheng, K. Kaznatcheev, W.E. Bailey
Journal of Applied Physics
111 07E321 (2012) (pdf) (journal)


Dependence of Gilbert damping on the ferromagnetic layer type in ferromagnet/Cu/Pt heterostructures
A. Ghosh, J.F. Sierra, S. Auffret, U. Ebels, W.E. Bailey
Applied Physics Letters 98 052508 (2011)
(pdf) (journal)


A compact apparatus for studies of element- and phase-resolved ferromagnetic resonance
D. Arena, Y. Ding, E. Vescovo, S. Zohar, Y. Guan, W.E. Bailey
Review of Scientific Instruments 80 083903 (2009)
(pdf) (journal)

Interface-related damping in polycrystalline Ni81Fe19/Cu/Co93Zr7
S. Zohar and W.E. Bailey
Journal of Applied Physics 105 07D309 (2009)
(pdf) (journal)

Element-specific spin and orbital moments in Fe1-xVx thin films
Y. Guan, C. Scheck, and W.E. Bailey
Journal of Magnetism and Magnetic Materials 321 1039 (2009)
(pdf) (journal)


Thin-film superparamagnetic resonance in a self-assembled g-Fe203 nanocrystal array
S. Zohar, K. Hultman, S. O'Brien, W.E. Bailey
Journal of Applied Physics 103 07D510 (2008)
(pdf) (journal)


Combined time-resolved XMCD and ferromagnetic resonance studies of magnetic alloys and multilayers
D.A. Arena, E. Vescovo, C.-C. Kao, Y. Guan and W.E. Bailey
Journal of Applied Physics 101 09C109 
(2007) (pdf) (journal) 


Ferromagnetic relaxation in (Ni81Fe19)1-xCux thin films: band filling at high Z
Y. Guan and W.E. Bailey
Journal of Applied Physics 101 101D94 
(2007) (pdf) (journal)  


Low relaxation rate in epitaxial vanadium-doped ultrathin iron films
Editors' Suggestion
C. Scheck, L. Cheng, I. Barsukov, Z. Frait, and W.E. Bailey
Physical Review Letters 98(11) 117601 (2007) (pdf) (journal) 


Phase and amplitude of element-specific moment precession in Ni81Fe19
Y. Guan, W.E. Bailey, E. Vescovo, C.-C. Kao, and D.A. Arena
Journal of Magnetism and Magnetic Materials 312(2) 374 (2006) (pdf) (journal) 

Weakly coupled motion of individual layers in ferromagnetic resonance
D.A. Arena, E. Vescovo, C.-C. Kao, Y. Guan, and W.E. Bailey
Physical Review B (Condensed Matter) 74(6) 064409 (2006) 
(pdf) (journal)


Low damping in epitaxial sputtered iron films 
C. Scheck, L. Cheng, and W.E. Bailey
Applied Physics Letters 88(25) 252510 (2006) (pdf) (journal) 

Dual-frequency ferromagnetic resonance
Y. Guan and W.E. Bailey
Review of Scientific Instruments 77 (6) (2006)
(pdf) (journal) (cond-mat)


Ion implantation of rare-earth dopants in ferromagnetic thin films 
V. Dasgupta*, N. Litombe, W. E. Bailey, and H. Bakhru
Journal of Applied Physics 99 08G312 (2006) (pdf) (journal)


Comparison of time-resolved XMCD measurements in reflection and transmission
for layer-specific precessional dynamics measurements
Y. Guan*, W.E. Bailey, C.-C. Kao, E. Vescovo, and D.A. Arena
Journal of Applied Physics 99 08J305 (2006) (pdf) (journal)



Transmission-mode XMCD characterization of moment alignment in Tb-doped Ni81Fe19 
Y. Guan, Z. Dios, D.A. Arena, L. Cheng, and W. E. Bailey
Journal of Applied Physics 97 10A719 (2005) (pdf) (journal)


Experimental separability of channeling GMR in Co/Cu/Co 
W.E. Bailey, S.E. Russek, X.-G. Zhang, W. H. Butler
Physical Review B (Condensed Matter) 72 012409 (2005) (pdf) (journal)



Precessional dynamics of elemental moments in a ferromagnetic alloy 
W. E. Bailey, L. Cheng, D. Keavney, C.-C. Kao, E. Vescovo, D. Arena
Physical Review B (Condensed Matter) 70 172403 (2004) (pdf) (journal)


Systematic control of magnetic damping in doped / undoped bilayer thin films
H. Song, L. Cheng, W.E. Bailey
Journal of Applied Physics; 95(11), 6592 (2004) (pdf) (journal)


Precessional frequency tuning in Ni81Fe19/Ni81Fe19:Eu bilayers
L. Cheng, H. Song, W.E. Bailey
IEEE Transactions on Magnetics 40(4) 2350 (2004)(pdf) (journal)



Dopants for independent control of precessional frequency and damping in Ni81Fe19(50nm)

S.G. Reidy, L. Cheng, W. E. Bailey
Applied Physics Letters 82, 1254 (2003) (pdf) (journal)

Refereed Conference Proceedings

Design of coupled power inductors with crossed-anisotropy magnetic core for integrated power conversion

N. Sturcken, R. Davies, C. Cheng, W.E. Bailey, K. Shepard
IEEE Applied Power Electronics Conference and Exposition (APEC), 417 (2012) 
(pdf) (journal) 

Synchronous (lock-in) measurement techniques for magnetic contrast enhancement in STXM

K. Kaznatcheev, D. Bertwistle, C. Cheng, S. Zohar, W.E. Bailey

AIP Conference Proceedings (USA) 1365 333 (2011)

Ph.D. Dissertations:

Yi Li (Sep 2015)

Cheng Cheng (Dec 2013) (pdf) 

Abhijit Ghosh (at UJF)

Sioan Zohar (Mar 2009)

Ultrafast magnetization dynamics in ferromagnetic ultrathin films and heterostructures
Yongfeng Guan, Ph.D. dissertation, Applied Physics, Columbia University, Deposited Jan. 2008


Materials-based control of ultrafast relaxation in magnetic thin films
Lili Cheng, Ph.D. dissertation, Materials Science, Columbia University, Deposited Jan. 2006


XMCD characterization of rare-earth dopants in Ni81Fe19(50nm): microscopic basis of engineered damping
W.E. Bailey, L. Cheng, H. Song
e-print: http://arxiv.org/abs/cond-mat/0403627



Selected doctoral / postdoctoral papers (pre-Columbian) 

"Magnetostriction and angular dependence of ferromagnetic resonance linewidth in Tb-doped Ni81Fe19 thin films," S.E. Russek, P. Kabos, R.D. McMichael, C.G. Lee, W.E. Bailey,  R. Ewasko, R.; S.C. Sanders, Journal of Applied Physics 91, pp. 8859-62 (2002)(pdf) (journal)

"Control of magnetization dynamics in Ni81Fe19(50nm) through the use of rare-earth dopants," W. Bailey, P. Kabos, F. Mancoff, S.E. Russek,IEEE Transactions on Magnetics 37(4), pp. 1749-55 (2001) (pdf) (journal)

"Electronic scattering from Co/Cu interfaces: in-situ measurement and comparison with theory,"  W.E. Bailey, S.X. Wang, E. Yu. Tsymbal Physical Review B (Condensed Matter) 61, pp. 1330-5 (2000) (pdf) (journal)

"Surface scattering and giant magnetoresistance: in-situ resistance and magnetoresistance experiments,"  W.E. Bailey Ph.D. Dissertation, Stanford University Deposited May 2000 (pdf)