Manipulate[
Plot[-2 t Cos[ka], {ka, -3, 3}, Frame -> True, Axes -> False,
FrameTicks -> {Range[-3, 3], {-2 t , -t, 0, t, 2 t}},
FrameLabel -> {Style["K a", Bold, 16],
Style["\!\(\*SubscriptBox[\(\[CurlyEpsilon]\), \(k\)]\)", Bold,
16]}, FrameStyle -> Directive[Black, Bold, Thick],
PlotLabel ->
Style["\!\(\*SubscriptBox[\(\[CurlyEpsilon]\), \
\(k\)]\)=-2tCos[Ka]", Bold, 16, Red]], {t, 1, 4}]
![](http://imgsrc.baidu.com/forum/w%3D580/sign=82794777d02a60595210e1121835342d/803eee24b899a9019f7ef0881a950a7b0308f5d0.jpg)