941 research outputs found
[[alternative]]The observation of magneto-optic Kerr effect for Ni(100)
No full text[[abstract]]表面磁光柯爾效應(surface magneto-optic Kerr effect，SMOKE)是研究
磁性超薄膜表面磁性的新探測技術。本人將先行於空氣中自行設計、建造
SMOKE的實驗裝置，且先在空氣中測試Ni(100)晶片的柯爾效應，完成磁滯
曲線的測定，並找出影響柯爾訊號強弱的參數，確定出量測上的最佳參數
控制，以為超高真空環境下的SMOKE量測系統之準備。在我們的系統中，
檢偏器角度在0.3-0.7度時有最好的柯爾訊號與背景比例。量測縱向柯爾
訊號時，宜選擇較大的入射角，但有其上限，不能超過60度左右以上，反
之，量測法線方向柯爾訊號時，入射角的選擇則愈小愈好，愈能擁有較強
的柯爾訊號強度。所測得之Ni(100)晶片之磁滯曲線，表現出低殘磁、低
矯頑力、低磁滯能量損耗的特性，我們另以縱向柯爾效應 ,試圖找出
Ni(100)面上的結構對稱性，結果顯示柯爾效應亦能指出Ni(100)面為四對
稱的結構，且原子最接近的方向為Ni(100)面上之磁化易軸，即最高度對
稱的方向，而原子次接近的方向為Ni(100)面上第二易磁化的方向，原子
第三接近的方向則為 Ni(100)面上第三易磁化的方向。
The surface magneto-optic Kerr effect (SMOKE) is a new probe
for studying surface magnetism of ultrathin films. SMOKE is a
potent- ial technique, because SMOKE can measure hysteresis
curves of mo- nolayer-range magnetic films. Thus I established
a SMOKE measure- ment system in the air. I tested Kerr effect
of Ni(100) crystal and finished the measurement of hysteresis
curves. Determining the best parameter of the measurement was
also done. These provi- de for the preparation of SMOKE
measurement system in ultrahigh vacuum. For fitting the UHV
condition, the strength of the applied magne- tic field is
inverse proportional to the gap between the magnetic poles of
the electromagnet. Setting the analyzer angle to 0.3-0.7 degree
will give the best signal-to-background ratio in our system.
The longitudinal Kerr signal is more pronounced when the
incident angle is large, at least 55 degree. However, the polar
Kerr signal has opposite result. SMOKE hysteresis loops of
longitudinal Kerr effect and polar Kerr effect of Ni(100)
crystal are both very narrow. The behaviors of these hysteresis
curve show low remanence, low coercive force and low hysteresis
loss. For exploring the relationship between magnetization and
structures, we intend to find the symmetry of the Ni(100)
crystal by longitudinal Kerr effect. The result indicates that
Kerr effect can show fourfold rotation symmtery of the Ni(100)
crystal. And the easy axes of magnetization of the Ni(100)
plane is along the direction of the nearest-neighor atom. The
second easy axes of magnetization of the Ni(100) plane is along
the direction of the second neighbor atom. The third axes of
magnetization of the Ni(100) plane is along the direction of
the third neighbor atom.
The surface magneto-optic Kerr effect (SMOKE) is a new probe
Special and Differential Treatment: A Mechanism to Promote Development?
No full textMuch has been made of "special and differential" treatment in the Doha Development Round of WTO negotiations. In particular, a conscious effort has been made to infer that special and differential treatment will promote development. While special and differential treatment may be a necessary evil given developing countries' higher adjustment costs, dignifying it as a development mechanism plays into the hands of protectionist interests. In particular, by allowing a general increase in the ability of developing countries to isolate their economies, it may reduce the efficacy of important forces that prod institutional reforms in developing countries. As institutional reform is one of the keys to economic development, lionizing special and differential treatment in the WTO is likely to be counterproductive.development, institutional reform, protectionism, special and differential treatment, WTO, International Development,
Massively parallel coherent LiDAR using dissipative Kerr solitons
No full textWe demonstrate an architecture for massively parallel frequency-modulated continuous wave (FMCW) laser ranging (LiDAR) by transferring linear chirps of a single narrow linewidth laser onto all soliton comb teeth though generation of a dissipative Kerr soliton in an integrated Si3N4 microresonator. (C) 2020 The Author(s)LPQ
Spectral multiplexing of dissipative Kerr solitons in a single optical microresonator
No full textWe experimentally demonstrate that dissipative Kerr solitons generated in different spectral regions can stably coexist in a single optical microresonator enabling spectral multiplexing of soliton microcombs. (C) 2020 The Author(s)LPQ
Polynomial rings over Goldie-Kerr commutative rings
No full textAll rings in this paper are commutative, and
acc
⊥
\operatorname {acc} \bot
(resp.,
acc
⊕
\operatorname {acc} \, \oplus
) denotes the acc on annihilators (resp., on direct sums of ideals). Any subring of an
acc
⊥
\operatorname {acc} \bot
ring, e.g., of a Noetherian ring, is an
acc
⊥
\operatorname {acc} \bot
ring. Together,
acc
⊥
\operatorname {acc} \bot
and
acc
⊕
\operatorname {acc} \, \oplus
constitute the requirement for a ring to be a Goldie ring. Moreover, a ring
R
R
is Goldie iff its classical quotient ring
Q
Q
is Goldie. A ring
R
R
is a Kerr ring (the appellation is for J. Kerr, who in 1990 constructed the first Goldie rings not Kerr) iff the polynomial ring
R
[
x
]
R[x]
has
acc
⊥
\operatorname {acc} \bot
(in which case
R
R
must have
acc
⊥
\operatorname {acc} \bot
). By the Hilbert Basis theorem, if
S
S
is a Noetherian ring, then so is
S
[
x
]
S[x]
; hence, any subring
R
R
of a Noetherian ring is Kerr. In this note, using results of Levitzki, Herstein, Small, and the author, we show that any Goldie ring
R
R
such that
Q
=
Q
c
(
R
)
Q = {Q_c}(R)
has nil Jacobson radical (equivalently, the nil radical of
R
R
is an intersection of associated prime ideals) is Kerr in a very strong sense:
Q
Q
is Artinian and, hence, Noetherian (Theorems 1.1 and 2.2). As a corollary we prove that any Goldie ring
A
A
that is algebraic over a field
k
k
is Artinian, and, hence, any order
R
R
in
A
A
is a Kerr ring (Theorem 2.5 and Corollary 2.6). The same is true of any algebra
A
A
over a field
k
k
of cardinality exceeding the dimension of
A
A
(Corollary 2.7). Other Kerr rings are: reduced
acc
⊥
\operatorname {acc} \bot
rings and valuation rings with
acc
⊥
\operatorname {acc} \bot
(see 3.3 and 3.4).</p
Thickness dependent enhancement of the polar Kerr rotation in Co magnetoplasmonic nanostructures
No full textLarge surface plasmon polariton assisted enhancement of the magneto-optical activity has been observed in the past, through spectral measurements of the polar Kerr rotation in Co hexagonal antidot arrays. Here, we report a strong thickness dependence, which is unexpected given that the Kerr effect is considered a surface sensitive phenomena. The maximum Kerr rotation was found to be -0.66 degrees for a 100 nm thick sample. This thickness is far above the typical optical penetration depth of a continuous Co film, demonstrating that in the presence of plasmons the critical lengthscales are dramatically altered, and in this case extended. We therefore establish that the plasmon enhanced Kerr effect does not only depend on the in-plane structuring of the sample, but also on the out-of-plane geometrical parameters, which is an important consideration in magnetoplasmonic device design. (c) 2019 Author(s)
Kerr Comb-based Transfer Oscillator for Ultralow Noise Photonic Microwave Synthesis
No full textWe perform optical frequency division of an ultra-stable laser by using a crystalline-based Kerr frequency comb as a transfer oscillator. We demonstrate absolute phase noise levels of -110 dBc/Hz at 200-Hz offset from a 14 GHz carrier. (C) 2019 The Author(s)LPQ
Real-time correlators and hidden conformal symmetry in the Kerr/CFT correspondence
No full textIn this paper, we study the real-time correlators in Kerr/CFT, in the low frequency limit of generic non-extremal Kerr(-Newman) black holes. From the low frequency scattering off Kerr-Newman black holes, we show that for the uncharged scalar scattering, there exists hidden conformal symmetry on the solution space. Similar to Kerr case, this suggests that the Kerr-Newman black hole is dual to a two-dimensional CFT with central charges c(L) = c(R) = 12J and temperatures T-L = (r(+)+ r(-))-Q(2)/M/4 pi a, T-R = r(+)-r(-)/4 pi a. Using the Minkowski prescription, we compute the real-time correlators of a charged scalar and find perfect match with CFT prediction. We further discuss the low-frequency scattering of photons and gravitons by a Kerr black hole and find that their retarded Green's functions are in good agreement with CFT prediction. Our study shows that hidden conformal symmetry in the solution space is essential to set up and check the Kerr/CFT correspondence.Physics, Particles & FieldsSCI(E)28ARTICLE6nul
Effects of higher-order Kerr nonlinearity and plasma diffraction on multiple filamentation of ultrashort laser pulses in air
No full textThe effect of higher-order Kerr nonlinearity on channel formation by, and filamentation of, ultrashort laser pulses propagating in air is considered. Filament patterns originating from multiphoton ionization of the air molecules with and without the higher-order Kerr and molecular-rotation effects are investigated. It is found that diverging multiple filaments are formed if only the plasma-induced defocusing effect is included. In the presence of the higher-order Kerr effects, the light channel can exist for a long distance. The effect of noise on the filament patterns is also discussed. (C) 2013 AIP Publishing LLC.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000322535400015&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Physics, Fluids & PlasmasSCI(E)EI3ARTICLE7null2
Simplified analytic formulae for magneto-optical Kerr effects in ultrathin magnetic films
No full textExpressions are presented for various magneto-optical Kerr effects in the ultrathin film limit with arbitrary magnetization direction by considering the multiple reflections within an optically thin film. The Kerr effect of p- and s-polarization consists of products of two factors: the prefactor, dependent only on the optical parameters of the system, and the main factor of the polar Kerr effect for normal incidence in the ultrathin limit. (C) 1999 Elsevier Science B.V. All rights reserved.This work was supported by the Creative Research Initiatives of the Ministry of Science and Technology of Korea, and
one author (CYY) wishes to acknowledge the financial support of the Korea Research Foundation made in program
Year 1997, and the hospitality of Argonne National Laboratory. Argonne was supported by the US Department of
Energy, BES-Material Science, under contract No. W-31-109-ENG-38
- …
